Re: gEDA-user: buzzing board
I got the new parts today. Redux: Adding 100uF electrolytic, swapping in 10u 25v 1206 ceramic did NOT get rid of the buzzing, just reduced it a little. Swapping in 10u 16v 1206 tantalum with the 100u DID get rid of the buzzing, both the low pitch and high. There's still 80mV P-P spikes on the line[*] at 8.3KHz (line refresh rate) but that's 6X better than the 500mV ripple it used to have. Lesson: for heavy-noisy loads at audible frequencies, you need sufficient non-ceramic decoupling before (or instead of) the ceramics. [*] http://www.delorie.com/electronics/alarmclock/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Put them sideways. Then you can put two Tants. in the one footprint. Assuming there is enough metal at the edge of the bottom, there has been in the past. There isn't. The metal is narrower than the cap. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Thursday 27 September 2007 08:09:34 pm DJ Delorie wrote: to reduce the peaks even more you may double up your tants if that is possible with your parts/layout. Not really. I can double up ceramics because the metal goes all the way around, but for the tants the metal is only on the bottom. Plus, I'm already putting 1206 caps on 0805 footprints. It just barely fits. Put them sideways. Then you can put two Tants. in the one footprint. Assuming there is enough metal at the edge of the bottom, there has been in the past. We, the Willing; Lead by the Unknowing; Are doing the impossible for the Ungrateful. We have done so much, for so long, with so little. We are now qualified to do anything, with nothing, forever. - Preface to Murphy's Laws. :-) ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Copper Tape! :-P Inside joke, Copper Tape seems to be the duct tape of my place. On 9/28/07, DJ Delorie [EMAIL PROTECTED] wrote: to reduce the peaks even more you may double up your tants if that is possible with your parts/layout. Not really. I can double up ceramics because the metal goes all the way around, but for the tants the metal is only on the bottom. Plus, I'm already putting 1206 caps on 0805 footprints. It just barely fits. The oled has a fairly long flex on it, about 4 inches, so I can only hope that the chip has its own decoupling caps nearby it if it's that critical. The +12v supply is only for the LEDs themselves, not the logic. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
The PCB for my alarm clock buzzes. Having poked and prodded, and getting a piezo unit that did nothing, I finally figured it out (the trick was to use a nail, not a toothpick, to poke and prod - I was using that as a better sound conductor for the piezo). There are not one but TWO buzzing caps. If I replace both of them with electrolytics, the buzzing goes away. If I replace them both with two new ones of the same type/size, it still buzzes. The caps are 4.7uF 16v. They're decoupling/bypass for a +12v rail (well, one is, the other is VcomH, which seems to be 7v). They're the biggest 0805's with that voltage rating. I can fit a 1206 in that spot. If I replace those with 10uF 25v, do you think they'll not buzz? Another alternative is 22uF 16v. I don't know if the buzz is due to insufficient capacitance, or damage due to being too close to the voltage rating. Alternatively, I can stack two 10uFs on top of each other to make 20uF 25v, but that's ugly. 1210's won't fit. Note that adding a 47uF 35v electrolytic across the 4.7u reduces the noise greatly. In fact, a 4.7u electrolytic helps much more than a second 4.7u ceramic. If I replace just the +12v cap with a 22u elec, the +7 cap still buzzes. I suspect the elec alone can't react fast enough to get rid of the ripple. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Wed, Sep 19, 2007 at 01:30:33PM -0400, DJ Delorie wrote: The PCB for my alarm clock buzzes. If I replace just the +12v cap with a 22u elec, the +7 cap still buzzes. I suspect the elec alone can't react fast enough to get rid of the ripple. Or is it reacting too quickly? Some power supplies need a minimum ESR so that the output cap acts as an RC filter. Your electrolytic cap is almost certainly higher ESR than what you had in there. Try air-wiring in your original cap with 1-5R and see what happens. -- Ben Jackson AD7GD [EMAIL PROTECTED] http://www.ben.com/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
DJ Delorie wrote: The caps are 4.7uF 16v. They're decoupling/bypass for a +12v rail (well, one is, the other is VcomH, which seems to be 7v). They're the biggest 0805's with that voltage rating. I can fit a 1206 in that spot. If I replace those with 10uF 25v, do you think they'll not buzz? I bet no buzzing -- different C and different mass, and both bigger, not a trade off that would have a similar resonance. Changing the masses by adding anything will probably stop the resonant sounds. John G -- Ecosensory Austin TX tinyOS devel on: ubuntu Linux; tinyOS v2.0.2; telosb ecosens1 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Or is it reacting too quickly? Some power supplies need a minimum ESR so that the output cap acts as an RC filter. The LDO has its own bypass cap (0.1u) at its terminals. The 4.7u is after the transistor that enables the rail to the OLED. It buzzes with both PNP and P-MOS, and those should provide sufficient resistance to avoid ringing that way. Besides, as I've said before, the ringing's waveform corresponds to the data on the OLED, like a video signal. It's not a constant ripple like a power supply problem, and goes away when the oled is filled with all dark pixels. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
The caps are 4.7uF 16v. They're decoupling/bypass for a +12v rail (well, one is, the other is VcomH, which seems to be 7v). They're the biggest 0805's with that voltage rating. What dielectric are those ceramic caps? Y5V, X5R, X7R? ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
What dielectric are those ceramic caps? Y5V, X5R, X7R? X5R ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On 9/19/07, DJ Delorie [EMAIL PROTECTED] wrote: Besides, as I've said before, the ringing's waveform corresponds to the data on the OLED, like a video signal. It's not a constant ripple like a power supply problem, and goes away when the oled is filled with all dark pixels. Have you looked at the voltage and current out of the power supply ss you start to fill the OLED? (* jcl *) -- http://www.luciani.org ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Sep 19, 2007, at 11:42 AM, DJ Delorie wrote: What dielectric are those ceramic caps? Y5V, X5R, X7R? X5R (Possibly) Interesting article about the piezo-electric effect in ceramic capacitors: http://www.kemet.com/kemet/web/homepage/kfbk3.nsf/vaFeedbackFAQ/ 242F5F2E69DCEC7485256EDF004CA495 -a ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
(Possibly) Interesting article about the piezo-electric effect in ceramic capacitors: Most relevant part of that article, Use a part with thicker dielectric, usually corresponding to a higher voltage rating. This reduces the voltage gradient, which reduces piezoelectric noise, if the package size increase is acceptable. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Most relevant part of that article, Use a part with thicker dielectric, usually corresponding to a higher voltage rating. This reduces the voltage gradient, which reduces piezoelectric noise, if the package size increase is acceptable. What about switching to tantalums? I can fit the EIA 3216 (1206-sized) parts in that slot, allowing a 10uF 16v tant instead of the 22uf 16v (or 10uF 25v) ceramic. Maybe I should find a spot on the back of the board for an electrolytic :-P Or I could buy a handful of each part type and keep experimenting :-) ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Andy Peters wrote: Tantalums will work. Just make sure you get surge rated parts. Otherwise, watch out for explosions at power-up. 3 ohms/volt dropper (5v = 15R dropper) to limit the surge was the standard I learnt and still use. Suitably adjusted/amended to allow for the load current. However I can not find the design notes that the value comes from, I have got them somewhere. The likely source is a Siemens databook from the 1980's. -- Regards Richard ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Sep 19, 2007, at 1:12 PM, DJ Delorie wrote: Most relevant part of that article, Use a part with thicker dielectric, usually corresponding to a higher voltage rating. This reduces the voltage gradient, which reduces piezoelectric noise, if the package size increase is acceptable. What about switching to tantalums? I can fit the EIA 3216 (1206-sized) parts in that slot, allowing a 10uF 16v tant instead of the 22uf 16v (or 10uF 25v) ceramic. Tantalums will work. Just make sure you get surge rated parts. Otherwise, watch out for explosions at power-up. -a ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Sep 19, 2007, at 1:34 PM, DJ Delorie wrote: Tantalums will work. Just make sure you get surge rated parts. Hmmm... how would I know? That's not one of the checkboxes on the digikey search engine. Sometimes catalog searches don't tell all. Kemet does have a surge-robust family, the T495 series. Under tantalums (http://www.kemet.com/kemet/web/homepage/ kechome.nsf/weben/products#sur-tan) look for Surge robust parts: http://www.kemet.com/kemet/web/homepage/kechome.nsf/weben/ 5CC0F4F059FD0E92CA2570A500160921/$file/F3102_T495.pdf DigiKey search: http://search.digikey.com/scripts/DkSearch/dksus.dll? lang=ensite=USkeywords=Kemet+Tantalum+T495x=0y=0 Good luck, -a ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Kemet does have a surge-robust family, the T495 series. http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=ensite=USkeywords=Kemet+Tantalum+T495x=0y=0 Grr, nothing small enough. OTOH, would the LDO limit the inrush current? ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
It should. The other thing to check is ripple: if you're getting enough to make a ceramic sing, the ripple current might be a problem for Ta. Check the ripple voltage and frequency across the cap and use the resistance and capacitance ratings to deduce a current. Yeah, the ripple voltage is pretty high, about 0.5vpp at 4.7uF and 14mA average draw. Hence my other thought, which was a big electrolytic and a medium sized cermic/tant. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
can you capture a current trace, knowing that information will provide us an ability to actually calculate the required capacitance. Where i work we do not use tantalum caps because there down sides are pretty big in terms of safety. when you over work a tant, they get very hot. It should. The other thing to check is ripple: if you're getting enough to make a ceramic sing, the ripple current might be a problem for Ta. Check the ripple voltage and frequency across the cap and use the resistance and capacitance ratings to deduce a current. Yeah, the ripple voltage is pretty high, about 0.5vpp at 4.7uF and 14mA average draw. Hence my other thought, which was a big electrolytic and a medium sized cermic/tant. If you have that much ripple, you need more capacitance. more of a reason to have a current trace. a high resolution voltage trace would also give the volts per second to deduce the current, knowing the ESR. Steve On Sep 19, 2007, at 10:30 AM, DJ Delorie wrote: The PCB for my alarm clock buzzes. Having poked and prodded, and getting a piezo unit that did nothing, I finally figured it out (the trick was to use a nail, not a toothpick, to poke and prod - I was using that as a better sound conductor for the piezo). There are not one but TWO buzzing caps. If I replace both of them with electrolytics, the buzzing goes away. If I replace them both with two new ones of the same type/size, it still buzzes. The caps are 4.7uF 16v. They're decoupling/bypass for a +12v rail (well, one is, the other is VcomH, which seems to be 7v). They're the biggest 0805's with that voltage rating. I can fit a 1206 in that spot. If I replace those with 10uF 25v, do you think they'll not buzz? Another alternative is 22uF 16v. I don't know if the buzz is due to insufficient capacitance, or damage due to being too close to the voltage rating. Alternatively, I can stack two 10uFs on top of each other to make 20uF 25v, but that's ugly. 1210's won't fit. Note that adding a 47uF 35v electrolytic across the 4.7u reduces the noise greatly. In fact, a 4.7u electrolytic helps much more than a second 4.7u ceramic. If I replace just the +12v cap with a 22u elec, the +7 cap still buzzes. I suspect the elec alone can't react fast enough to get rid of the ripple. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user smime.p7s Description: S/MIME cryptographic signature ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
What about switching to tantalums? I can fit the EIA 3216 (1206-sized) parts in that slot, allowing a 10uF 16v tant instead of the 22uf 16v (or 10uF 25v) ceramic. Using a tantalum should solve the problem. From the same article, Use a different type of capacitor, such as tantalum ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
can you capture a current trace, knowing that information will provide us an ability to actually calculate the required capacitance. 10 ohm resistor between the LDO and the control transistor (LDO - resistor - P-MOS - cap - OLED). ~300mV Vpp ripple across the resistor, 30mV to 300mV absolute. That would be 3mA to 30mA That's at 8.4KHz It's not a sine wave; it's 15uS rise and 104uS fall. Voltage at that point is 12.1v with 0.43 Vpp ripple. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Ok, here's a random thought. What if the hotplate reflow delaminated one of the layers? You'd still need a cause, but it would make the cause's minimum size smaller. Of course, there's no *visible* effect on the pcb from the hotplate, not even a mild yellowing on the back. How good is the temp. control on your oven? I am not saying this is imposable just unlikely. More likely is that you added capacitance when you went from a bread board to the PCB or that interference that was physically more spread out got closer when you made the PCB layout. I notice the CPU is socketed could you please try powering up the board without it. -- http://www.coe.neu.edu/~efoss/ http://evanfoss.googlepages.com/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
How good is the temp. control on your oven? Er, zero control. I use a hotplate, which heats only the back of the board, so the solder melts before the chips get too hot. However, it's a $20 item, and basically has on and off settings. What I do is turn it on and wait. About 3 minutes later, the solder paste starts melting. It takes about 10-20 seconds for the whole board to be done after that, then I slide it off the hotplate onto a cooling rack. I notice the CPU is socketed could you please try powering up the board without it. Without the CPU, the oled won't power up. You're not supposed to apply +12v until you program all the timing parameters, else you burn out the OLED cells. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Going way back in this conversation. The OLED has noise on it 0.5V. What frequency? The switchers are opporating at 150KHz. What frequency is the buzzing? Could the two noise signals be mixing? Could a capacitor be humming like a tunning fork with respect to one or more of the noise signals? Steve Meier ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
The OLED has noise on it 0.5V. What frequency? Line redraw noise is about 7.8khz, with the waveform dependent on what's on the screen. That's the high pitched whine portion. 5.5ms of that noise, followed by 1.5ms of quiet, about 140Hz vertical refresh. That's the buzzing portion. The switchers are opporating at 150KHz. What frequency is the buzzing? Audible :-( Could a capacitor be humming like a tunning fork with respect to one or more of the noise signals? I've tried removing, and changing, the bypass cap on that supply rail. No change. Hmmm... I can try tweaking the refresh period. As soon as my son is done playing video games with my laptop. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
No oled no noise? with oled noise but comming from the board. Could it be the connector? On Fri, 2007-09-14 at 14:53 -0400, DJ Delorie wrote: The OLED has noise on it 0.5V. What frequency? Line redraw noise is about 7.8khz, with the waveform dependent on what's on the screen. That's the high pitched whine portion. 5.5ms of that noise, followed by 1.5ms of quiet, about 140Hz vertical refresh. That's the buzzing portion. The switchers are opporating at 150KHz. What frequency is the buzzing? Audible :-( Could a capacitor be humming like a tunning fork with respect to one or more of the noise signals? I've tried removing, and changing, the bypass cap on that supply rail. No change. Hmmm... I can try tweaking the refresh period. As soon as my son is done playing video games with my laptop. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
No oled no noise? with oled noise but comming from the board. Could it be the connector? I've poked the connector to no avail. I don't have a piezo element at the moment, else I might have better luck tracking down the actual source of the noise. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Sep 12, 2007, at 9:34 PM, DJ Delorie wrote: The PCB for my alarm clock buzzes. 2. What kind of components *can* make that kind of noise? 3. If you know what's causing it, how do I fix it? Once upon a time I was at the local rock venue doing a soundcheck and one of the musicians on stage said, Hey, there's a weird buzz coming from the monitors. I picked up my talkback mic and said, Really? What does it sound like? and then he said, Huh ... it just went away. I put down the talkback and then he said, Hey, it's back. I picked up the talkback, said, Huh! and he said, Now it's gone. I put the talkback down again, and he said, it's bck! The talkback was not muted but it was routed only to the stage monitors, so I couldn't hear the buzz. Turns out that I put the talkback mic on top of a Lexicon MIDI Remote Control box. I soloed the talkback into my headphones, and heard the buzz. I picked up the mic and the buzz went away. Put it back onto the MRC, and the buzz came back. H ... and the buzz was worst when it was right on top of the MRC's LCD. Very weird. -a ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
... and the buzz was worst when it was right on top of the MRC's LCD. Very weird. I've been following this sort of off and on, so forgive me if this has already been mentioned. DJ, your LCD has a back light, doesn't it? I've seen touch-sensitive screens using flourescent back lights which are powered by several kV generated by an on-board switcher. I'd imagine the LCD display also has a switcher on it to generate the backlight, and if the display is an el-cheapo model, well, the switcher could have all kinds of noise-prone components on it. Just a thought. Stuart ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
DJ, your LCD has a back light, doesn't it? It's not an LCD. I chose OLEDs specifically because they didn't need a backlight. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Take a FFT of the sound. use this software or another like it. http://www.arachnoid.com/FFTExplorer/index.html use a good sound card if you can afford it. you could be hearing a beat frequency of 19th or 20th harmonic of the 7.8 kHz oled, and the 150kHz switcher 7.8 * 19 = 148.2kHz :-) welcome to the land of harmonics :-) Steve smime.p7s Description: S/MIME cryptographic signature ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Take a FFT of the sound. My scope has FFT built in. I just can't get a microphone to pick it up. you could be hearing a beat frequency of 19th or 20th harmonic of the 7.8 kHz oled, and the 150kHz switcher Except it happens when the switcher is off, too. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
mic pre-amps are more sensitive than you scope's input stage. perhaps not as accurate, but there made for low level signals. unless you are putting your microphone through a pre amp into your scope, you won't see such a quiet signal. i have done this with an iMic (http://www.griffintechnology.com/ products/imic/) and a cheap $2 microphone but you have to use a sound card with a mic input. we also made a sound proof box, out of MDF and mass loaded vinyl. if have some cinder blocks laying around, put the mic and the board on a concrete floor inside of that brick box and that should make it much quieter, by blocking ambient noise. Steve On Sep 14, 2007, at 4:15 PM, DJ Delorie wrote: Take a FFT of the sound. My scope has FFT built in. I just can't get a microphone to pick it up. smime.p7s Description: S/MIME cryptographic signature ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Thursday 13 September 2007 06:56:44 pm DJ Delorie wrote: My wife said the same thing. However, *this* board is going in my bedroom, on a table near my pillow, while I'm asleep. Do you really want all of that eletricmagnetic junk by your head? Louis Slesin of Microwave News states: It's become axiomatic that wide acceptance of non-thermal effects will come from developing biomedical therapies rather than from studying potential hazards. The health effects work is mostly sponsored by those who don't want to find any. And they usually don't... http://blog.wearablesmartsensors.com/energy_harvesting/20070624-080330-Potential-Wireless-Power-Health-Issues Has the links to the relivent references. There's nothing else in that room that makes noise, and Pat's already complaining about the buzzing sound coming from my old alarm clock. Rather than trying to find out what is buzzing, can you find out what is not buzzing, or make the problem worse to make it esier to find? ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Do you really want all of that eletricmagnetic junk by your head? The clock I'm replacing has a plain old motor in it. Isn't that giving out far more EM junk than some microelectronics? Rather than trying to find out what is buzzing, can you find out what is not buzzing, or make the problem worse to make it esier to find? So far, I haven't been able to affect the sound in any useful way, just a few useless ways. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
DJ Delorie wrote: Rather than trying to find out what is buzzing, can you find out what is not buzzing, or make the problem worse to make it esier to find? So far, I haven't been able to affect the sound in any useful way, just a few useless ways. The buzzing's audible, you said. You could put small rattly things on surfaces to detect where the motion is largest by making other harmonics suddenly apparent. Sound power is coming from motion... Think snare drum. What have you got that's like glass beads suspended on monofilament line? That would have a snare drum effect when lightly dragged across your board. Like an ultra-low-tech microphone-preamp-FFT-display-analysis chain that uses your eyes-ears-brain and a simpler snare drum tool instead. If you have on old Victrola with bamboo needles, you could take the head off and feel around with it for some amplification of the local vibrations... Steel needles might be trouble... John Griessen -- Ecosensory ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
I suggest stopping trying to solve this problem using itellect. At times shots in the dark workbest. Take your board outside at night and take your 22 with you set the board up in a safe spot and there in the dark aim for where the buzzing sound is comming from and fire. Repeat the last step until the buzzing sound stops. On Fri, 2007-09-14 at 20:14 -0500, John Griessen wrote: DJ Delorie wrote: Rather than trying to find out what is buzzing, can you find out what is not buzzing, or make the problem worse to make it esier to find? So far, I haven't been able to affect the sound in any useful way, just a few useless ways. The buzzing's audible, you said. You could put small rattly things on surfaces to detect where the motion is largest by making other harmonics suddenly apparent. Sound power is coming from motion... Think snare drum. What have you got that's like glass beads suspended on monofilament line? That would have a snare drum effect when lightly dragged across your board. Like an ultra-low-tech microphone-preamp-FFT-display-analysis chain that uses your eyes-ears-brain and a simpler snare drum tool instead. If you have on old Victrola with bamboo needles, you could take the head off and feel around with it for some amplification of the local vibrations... Steel needles might be trouble... John Griessen ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Friday 14 September 2007 09:00:33 pm DJ Delorie wrote: Do you really want all of that eletricmagnetic junk by your head? The clock I'm replacing has a plain old motor in it. Isn't that giving out far more EM junk than some microelectronics? There is a belief that modulated fields are worse than static fields. So far, I haven't been able to affect the sound in any useful way, just a few useless ways. If you don't have any Piezo sensors, as you have mentioned, do you have any old electronic phones you can sacrifice to get one? You could use a Ceramic Cap. as a sensor as well, as they are frequently made of Barium Titanate, same as the Piezo sensors. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Sep 14, 2007, at 9:43 PM, Steve Meier wrote: I suggest stopping trying to solve this problem using itellect. At times shots in the dark workbest. Take your board outside at night and take your 22 with you set the board up in a safe spot and there in the dark aim for where the buzzing sound is comming from and fire. Repeat the last step until the buzzing sound stops. soda - monitor DAMN YOU STEVE -- Dave McGuire Port Charlotte, FL Farewell Ophelia, 9/22/1991 - 7/25/2007 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Dave, You are just jealous that I come up with such elegent solutions (mine have even avoided caustic fluids liberaly mixed with copper). Yes I have a right to be smug since, I know others where thinking a shotgun approach. By the way you might want to put a plastic bag over your display before you open one of my tirades ;) This is the second one in a month you have trashed. Hmm, unless you put all food a side this might have made three? Steve M. Dave McGuire wrote: On Sep 14, 2007, at 9:43 PM, Steve Meier wrote: I suggest stopping trying to solve this problem using itellect. At times shots in the dark workbest. Take your board outside at night and take your 22 with you set the board up in a safe spot and there in the dark aim for where the buzzing sound is comming from and fire. Repeat the last step until the buzzing sound stops. soda - monitor DAMN YOU STEVE ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Sep 14, 2007, at 11:55 PM, Steve Meier wrote: You are just jealous that I come up with such elegent solutions (mine have even avoided caustic fluids liberaly mixed with copper). Yes I have a right to be smug since, I know others where thinking a shotgun approach. Well I suppose something as small as a .22cal might be considered an elegant solution in some circles. ;) By the way you might want to put a plastic bag over your display before you open one of my tirades ;) This is the second one in a month you have trashed. Hmm, unless you put all food a side this might have made three? This is a 23 Cinema Display...If it ever gets so bad that the lunch won't clean off completely, I'm sending the bill to YOU! ;) -Dave -- Dave McGuire Port Charlotte, FL Farewell Ophelia, 9/22/1991 - 7/25/2007 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Dave McGuire wrote: On Sep 14, 2007, at 11:55 PM, Steve Meier wrote: You are just jealous that I come up with such elegent solutions (mine have even avoided caustic fluids liberaly mixed with copper). Yes I have a right to be smug since, I know others where thinking a shotgun approach. Well I suppose something as small as a .22cal might be considered an elegant solution in some circles. ;) By the way you might want to put a plastic bag over your display before you open one of my tirades ;) This is the second one in a month you have trashed. Hmm, unless you put all food a side this might have made three? This is a 23 Cinema Display...If it ever gets so bad that the lunch won't clean off completely, I'm sending the bill to YOU! ;) -Dave soda - dave's monitor ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Sep 15, 2007, at 1:17 AM, Steve Meier wrote: You are just jealous that I come up with such elegent solutions (mine have even avoided caustic fluids liberaly mixed with copper). Yes I have a right to be smug since, I know others where thinking a shotgun approach. Well I suppose something as small as a .22cal might be considered an elegant solution in some circles. ;) By the way you might want to put a plastic bag over your display before you open one of my tirades ;) This is the second one in a month you have trashed. Hmm, unless you put all food a side this might have made three? This is a 23 Cinema Display...If it ever gets so bad that the lunch won't clean off completely, I'm sending the bill to YOU! ;) soda - dave's monitor Hey. HEY! -- Dave McGuire Port Charlotte, FL Farewell Ophelia, 9/22/1991 - 7/25/2007 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
At 00:34 -0400 13-09-2007, DJ Delorie wrote: 2. What kind of components *can* make that kind of noise? Ceramic capacitors, especially high-K ones (Y5V,Z5U), can exhibit signs of piezo-elektrickery. The supply decoupling banks of a prototype pulse laser driver of mine buzz like a trapped hornet when I fire it up. JDB. -- LART. 250 MIPS under one Watt. Free hardware design files. http://www.lartmaker.nl/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Ceramic caps on a switching power supply can have a pizeo eletric effect. Try poscaps or a tant. Hook up a microphone and take a fft of the sound a sound card can do it if you don't have a scope or spectrim analyzer. Did you cheap out on the inductor? Try potting them with something, I'd go for something non viscous, elastic and sticky. Sent from my iPhone On Sep 12, 2007, at 9:43 PM, Dave McGuire [EMAIL PROTECTED] wrote: On Sep 13, 2007, at 12:34 AM, DJ Delorie wrote: Ok, help me out with this one. The PCB for my alarm clock buzzes. It's really hard to tell which part is doing it, just from listening. The sound may be a combination of a high pitch whine and a 100hz buzz (the oled is 100hz). The buzzing is related to what's displayed on the OLED; the +12v to the oled has noise on it (0.5vpp) that corresponds to current draw. If I erase the screen, or run without the oled, or unplug the power jumper for it, the buzzing stops. However, adding more bypass on it (which gets rid of the noise) doesn't stop the buzzing, nor does shorting out the enabling transistor, nor bypassing the LDO. Removing the bypass cap doesn't make it worse. The OLED power supply is on the opposite end of the board (a few inches away) from the 3.3v switcher. Is it convenient to try putting an choke in series with the OLED's power supply line, with the OLED's bypass capacitor on the OLED side of the choke? I *think* the sound may be coming from the switching power supply (it has three power inductors in it), but neither the +15v power input nor the 3.3v rail have any noise on them (outside of the 150KHz from the switcher itself). Bypassing two of the inductors (the filter ones) does nothing. Pressing on any component does nothing. So, three questions: 1. How do you find out where such a noise is coming from, when everything is so close together? Neither a stethoscope nor a straw were helpful. I've only used those two methods, aside from probing around with an oscilloscope to look for the noise. One other trick that I've not tried (if anyone can comment on this I'd appreciate it) is to use an inductive pickup probe to look at the *current* waveforms on the supply lines to different parts of the circuit, and see what corresponds to the noise you're hearing. 2. What kind of components *can* make that kind of noise? Inductors and PCB traces, mainly...but I suppose nearly anything probably could, to one degree or another. 3. If you know what's causing it, how do I fix it? Hot glue, molten wax, conformal coating.. -Dave -- Dave McGuire Port Charlotte, FL Farewell Ophelia, 9/22/1991 - 7/25/2007 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
So do OLED displays buzz themselves ? No, it's definitely coming from the board somewhere. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Ceramic caps on a switching power supply can have a pizeo eletric effect. Try poscaps or a tant. The switcher caps are tantalum. There are also two electrolytic bulk caps, one on each side of the switcher. Probably the best view of these is here: http://www.delorie.com/electronics/alarmclock/20070908-board.html The OLED's LDO is in the far upper right in that photo. For the purposes of solving this problem, I put the design files here: http://www.delorie.com/electronics/alarmclock/20070913-design.zip Did you cheap out on the inductor? Not that I'm aware of. I used these: 495-2003-1-ND EPCOS B82464A4104K (100uH) PCD2089CT-NDPanasonic ELL-5PM3R0N (3uH) ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Does the switching power supply have a transformer? No, it's a simple buck converter. Does the frequency change when you change load? No, just intensity. Is the output noise within the power supply specification? The switcher's output is pretty clean, about 7 mVpp at 150 kHz. The OLED uses a +12 LDO; the oled side is pretty dirty (0.5 Vpp) but adding a huge cap to it (which nearly eliminates the noise) doesn't change the sound. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Thu, 13 Sep 2007 11:38:57 -0400 DJ Delorie [EMAIL PROTECTED] wrote: Did you cheap out on the inductor? Not that I'm aware of. I used these: By far the most probable cause is the inductor. I've made quite a few switchers, and several of them caused problems. I'm not so preoccupied with the noise by itself, but more by the possibility this may cause chafing and shorts on the long haul. The buzzing may appear only if a certain load (lower _or_ higher) is placed on the supply, as the switcher frequency passes through some resonance in the windings (even they should ideally be impregated). Even 'fixed frequency' switchers vary a little... John ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
take your 3.3 volt bench supply and bypass the 3.3v switcher. i have heard others suggest this i think in the thread. if the noise continues you know it is another source. Steve On Sep 13, 2007, at 11:58 AM, John Coppens wrote: On Thu, 13 Sep 2007 11:38:57 -0400 DJ Delorie [EMAIL PROTECTED] wrote: Did you cheap out on the inductor? Not that I'm aware of. I used these: By far the most probable cause is the inductor. I've made quite a few switchers, and several of them caused problems. I'm not so preoccupied with the noise by itself, but more by the possibility this may cause chafing and shorts on the long haul. The buzzing may appear only if a certain load (lower _or_ higher) is placed on the supply, as the switcher frequency passes through some resonance in the windings (even they should ideally be impregated). Even 'fixed frequency' switchers vary a little... John ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
TOP POST - bad andrew Have you tried the contact microphone (pizeo buzzer) yet to narrow down the location ? Hook it up to your sound card if you don't have a great scope. I am assuming it is in the bottom right hand corner of the picture where it looks like the switcher and the SM inductors are that it seems to be coming from. Maybe you could consider one more culprit in that corner you may have over looked - the DC plug. DJ Delorie wrote: Ceramic caps on a switching power supply can have a pizeo eletric effect. Try poscaps or a tant. The switcher caps are tantalum. There are also two electrolytic bulk caps, one on each side of the switcher. Probably the best view of these is here: http://www.delorie.com/electronics/alarmclock/20070908-board.html The OLED's LDO is in the far upper right in that photo. For the purposes of solving this problem, I put the design files here: http://www.delorie.com/electronics/alarmclock/20070913-design.zip Did you cheap out on the inductor? Not that I'm aware of. I used these: 495-2003-1-ND EPCOS B82464A4104K (100uH) PCD2089CT-NDPanasonic ELL-5PM3R0N (3uH) ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Have you tried the contact microphone (pizeo buzzer) yet to narrow down the location ? Hook it up to your sound card if you don't have a great scope. I got an electret mic working, but it didn't pick up anything off the board. Hmmm... do I even *have* a peizo buzzer? I've got a magnetic transducer off an old motherboard... I guess I could pick up something at RS next time I'm out. I am assuming it is in the bottom right hand corner of the picture where it looks like the switcher and the SM inductors are that it seems to be coming from. The bottom right (the one with the three SMT inductors) is the 3.3v switcher. In that photo, the TOP right is the +12v LDO for the OLED. Maybe you could consider one more culprit in that corner you may have over looked - the DC plug. Nudging the power jack does nothing. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On 9/13/07, DJ Delorie [EMAIL PROTECTED] wrote: I am assuming it is in the bottom right hand corner of the picture where it looks like the switcher and the SM inductors are that it seems to be coming from. The bottom right (the one with the three SMT inductors) is the 3.3v switcher. In that photo, the TOP right is the +12v LDO for the OLED. Pressing on each inductor with a wooden dowel didn't change the buzzing? (* jcl *) --- http://www.luciani.org ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Pressing on each inductor with a wooden dowel didn't change the buzzing? Nope. However, pressing at random places on the board does, but only because it changes the (I think) wave inteference patterns. I.e. it has no effect if your ear is close enough, but further away, the volume of the sound is sensitive to where your ear is. Makes it rather annoying to debug. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On 9/13/07, DJ Delorie [EMAIL PROTECTED] wrote: Pressing on each inductor with a wooden dowel didn't change the buzzing? Nope. However, pressing at random places on the board does, but only because it changes the (I think) wave inteference patterns. I.e. it has no effect if your ear is close enough, but further away, the volume of the sound is sensitive to where your ear is. Makes it rather annoying to debug. Is the board in the Panavise while it is buzzing? (* jcl *) -- http://www.luciani.org ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Is the board in the Panavise while it is buzzing? I've already thought of that. It makes the same sound if I take it out and hold it in my hands, which are neither magnetic nor stiff like the panavise. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On 9/13/07, DJ Delorie [EMAIL PROTECTED] wrote: Is the board in the Panavise while it is buzzing? I've already thought of that. It makes the same sound if I take it out and hold it in my hands, which are neither magnetic nor stiff like the panavise. Do you have a picture that shows the bottom of the board populated? (* jcl *) -- http://www.luciani.org ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
The only thing on the bottom of the board is a couple of bypass caps (most are on the top) and some of the ethernet bias circuitry. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
take your 3.3 volt bench supply and bypass the 3.3v switcher. No change! I took out the switcher and wired an LDO into the test points, same symptoms as before. The LDO got hot, which is why I went with a switcher - it's got to drop 12-17v down to 3.3v with enough current to drive the cpu, ethernet, mp3 chip, eeproms, and oled logic. But the board worked, and still buzzed. So, it's NOT the inductors! Whew. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Sep 13, 2007, at 6:52 PM, DJ Delorie wrote: So, it's NOT the inductors! Whew. no not whew. tougher. Tougher to figure out, but at least I don't have to design a new power supply. Hey DJ...Look at it this way. If you can really hear a faint buzzing sound coming from your alarm clock, there's clearly not enough equipment running in your house. (real computers have wheels) -Dave -- Dave McGuire Port Charlotte, FL Farewell Ophelia, 9/22/1991 - 7/25/2007 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Hey DJ...Look at it this way. If you can really hear a faint buzzing sound coming from your alarm clock, there's clearly not enough equipment running in your house. My wife said the same thing. However, *this* board is going in my bedroom, on a table near my pillow, while I'm asleep. There's nothing else in that room that makes noise, and Pat's already complaining about the buzzing sound coming from my old alarm clock. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
So, it's NOT the inductors! Whew. no not whew. tougher. Tougher to figure out, but at least I don't have to design a new power supply. Or explain why current on the +12 rail affects the 3.3v ldo on the other end of the board. At least now it makes more sense; if it was the switcher it wouldn't have made sense, since the switcher isn't involved in the OLED's +12v supply. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Sep 13, 2007, at 3:36 PM, DJ Delorie wrote: So, it's NOT the inductors! Whew. no not whew. tougher. Steve ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Sep 13, 2007, at 6:56 PM, DJ Delorie wrote: Hey DJ...Look at it this way. If you can really hear a faint buzzing sound coming from your alarm clock, there's clearly not enough equipment running in your house. My wife said the same thing. However, *this* board is going in my bedroom, on a table near my pillow, while I'm asleep. There's nothing else in that room that makes noise, and Pat's already complaining about the buzzing sound coming from my old alarm clock. I recommend the following: DEC PDP-11/34a 2 RL02 disk drives 1 RK07 disk drive 1 TU16 magtape drive A system like that, running in my bedroom when I was 16-17, kept me sleeping like a baby. Mmm, that low rumble and all those muffin fans. It only pulled about 16 amps, so it helped in the winter too. With one of those, you'll never hear the alarm clock. -Dave -- Dave McGuire Port Charlotte, FL Farewell Ophelia, 9/22/1991 - 7/25/2007 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
spaghetti - keyboard BWHAHAH!! On Sep 13, 2007, at 7:26 PM, Steve Meier wrote: Hey you have two data points that alarm clocks must by their nature buzz! Steve M. On Thu, 2007-09-13 at 18:56 -0400, DJ Delorie wrote: Hey DJ...Look at it this way. If you can really hear a faint buzzing sound coming from your alarm clock, there's clearly not enough equipment running in your house. My wife said the same thing. However, *this* board is going in my bedroom, on a table near my pillow, while I'm asleep. There's nothing else in that room that makes noise, and Pat's already complaining about the buzzing sound coming from my old alarm clock. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user -- Dave McGuire Port Charlotte, FL Farewell Ophelia, 9/22/1991 - 7/25/2007 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Hey you have two data points that alarm clocks must by their nature buzz! Steve M. On Thu, 2007-09-13 at 18:56 -0400, DJ Delorie wrote: Hey DJ...Look at it this way. If you can really hear a faint buzzing sound coming from your alarm clock, there's clearly not enough equipment running in your house. My wife said the same thing. However, *this* board is going in my bedroom, on a table near my pillow, while I'm asleep. There's nothing else in that room that makes noise, and Pat's already complaining about the buzzing sound coming from my old alarm clock. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Also, replacing the PNP with a P-MOSFET doesn't change anything. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Hey you have two data points that alarm clocks must by their nature buzz! None of the other alarm clocks in the house buzz, though. Except when their alarms go off ;-) ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
What kind of alarm does your alarm clock use? It has an mp3 decoder in it, so you can pick anything from an annoying beep to a streaming radio station across the planet. http://www.delorie.com/electronics/alarmclock/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Not to be insulting but is the speaker connected? -- http://www.coe.neu.edu/~efoss/ http://evanfoss.googlepages.com/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Thu, Sep 13, 2007 at 06:52:49PM -0400, DJ Delorie wrote: Tougher to figure out, but at least I don't have to design a new power supply. Or explain why current on the +12 rail affects the 3.3v ldo on the other end of the board. Have you made sure that both ends of all the components are solidly attached? It'd be easier to miss something like that with a reflow build than if you'd personally touched each component with an iron. -- Ben Jackson AD7GD [EMAIL PROTECTED] http://www.ben.com/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Have you made sure that both ends of all the components are solidly attached? It'd be easier to miss something like that with a reflow build than if you'd personally touched each component with an iron. At this point, all the components on the +12v net have been manually soldered. Mostly because I've been swapping them in and out to see which ones cause changes. I also used a thicker paste mask this time, I think I ended up with more paste than optimal so it's pretty easy to tell they've been soldered. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
What kind of alarm does your alarm clock use? -- http://www.coe.neu.edu/~efoss/ http://evanfoss.googlepages.com/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Not to be insulting but is the speaker connected? Heh. No, the speakers are not connected. Yes, they do buzz if you leave the audio amps running. No, I don't leave them running, so they normally won't buzz when the alarm is off. There's a circuit from the cpu just to put the amps into standby mode just for this. At this point, no suggestion is silly enough to insult me. I'd much rather it be something stupid yet easily fixed, than something subtle that is hard to fix. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
I have had audio amplifiers and large transistors in general buzz on their own. Are you sure it is really on standby? -- http://www.coe.neu.edu/~efoss/ http://evanfoss.googlepages.com/ ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
I have had audio amplifiers and large transistors in general buzz on their own. Are you sure it is really on standby? Yes, I checked the control pin. I just tested it with the amps on, too. No change. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
One good way to address this and other such possibilities would be to start de-soldering each component that is not strictly necessary to drive the OLED. It doesn't bother me THAT much ;-) If you get down to just the CPU, OLED, and required support components, I would go so far as to remove the CPU and its required components, and solder on wires to drive the OLED from off-board. I have two more boards, plus the breadboard still works. Maybe I'll just let it go for now, and if it's the same on all three boards I'll worry about it then. But I'll try to remember to pick up a piezo thing at RS next time I'm over there. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Thu, 13 Sep 2007 17:23:56 -0400 DJ Delorie [EMAIL PROTECTED] wrote: The only thing on the bottom of the board is a couple of bypass caps (most are on the top) and some of the ethernet bias circuitry. The ethernet uses a galvanic isolation power supply? One of those XXv to 9v DC converters? Tried to eliminate that? It hasn't anything to do with the oled circuitry though... John ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
The ethernet uses a galvanic isolation power supply? One of those XXv to 9v DC converters? Tried to eliminate that? It hasn't anything to do with the oled circuitry though... It's an ENC28J60 with a pulsejack (internal magnetics). I.e. one chip, one RJ45, and a handful of 0603 discretes. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Thu, Sep 13, 2007 at 08:35:35PM -0400, evan foss wrote: I have had audio amplifiers and large transistors in general buzz on their own. Are you sure it is really on standby? One good way to address this and other such possibilities would be to start de-soldering each component that is not strictly necessary to drive the OLED. Do them one at a time, and test between each one. Sounds like a fun way to spend an afternoon. If you have a spare board and components, it might be easier to start from scratch, and add one thing at a time. (Which would also help catch bad solder joints.) If you get down to just the CPU, OLED, and required support components, I would go so far as to remove the CPU and its required components, and solder on wires to drive the OLED from off-board. Then you'd have it pretty well narrowed down, I'd say. -- Randall ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
P.S. Aren't you glad the minimum board buy at the PCB vendor was three? ;-) It wasn't. It was one. I have customers for the other two. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On 9/13/07, DJ Delorie [EMAIL PROTECTED] wrote: At this point, no suggestion is silly enough to insult me. * You could try freeze spray on individual components. If building up another board testing section by section doesn't help find the fault in your first board you could try operational burnin and/or temperature cycling. Of course by the end of your failure acceleration testing buzzing may be at the bottom of your list of problems to ECO ;-) (* jcl *) P.S. Aren't you glad the minimum board buy at the PCB vendor was three? ;-) -- http://www.luciani.org ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
unsolder them and slide an insulator between the pin and the pad. On Thu, 2007-09-13 at 22:18 -0400, DJ Delorie wrote: Or, try lifting the power pins one component at a time. And if it buzzes it must be oscillating and should be viewable with your oscope. Just tug on them, or unsolder them? ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
also re-read the data sheets any chance you tied a reference output to ground? On Thu, 2007-09-13 at 22:18 -0400, DJ Delorie wrote: Or, try lifting the power pins one component at a time. And if it buzzes it must be oscillating and should be viewable with your oscope. Just tug on them, or unsolder them? ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
also re-read the data sheets any chance you tied a reference output to ground? Which chips would have these? The OLED has a few pins that must remain floating and they're floating. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Or, try lifting the power pins one component at a time. And if it buzzes it must be oscillating and should be viewable with your oscope. Just tug on them, or unsolder them? ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Or, try lifting the power pins one component at a time. And if it buzzes it must be oscillating and should be viewable with your oscope. Steve M. On Thu, 2007-09-13 at 20:42 -0400, Randall Nortman wrote: On Thu, Sep 13, 2007 at 08:35:35PM -0400, evan foss wrote: I have had audio amplifiers and large transistors in general buzz on their own. Are you sure it is really on standby? One good way to address this and other such possibilities would be to start de-soldering each component that is not strictly necessary to drive the OLED. Do them one at a time, and test between each one. Sounds like a fun way to spend an afternoon. If you have a spare board and components, it might be easier to start from scratch, and add one thing at a time. (Which would also help catch bad solder joints.) If you get down to just the CPU, OLED, and required support components, I would go so far as to remove the CPU and its required components, and solder on wires to drive the OLED from off-board. Then you'd have it pretty well narrowed down, I'd say. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
can I see a bom or schematic? On Thu, 2007-09-13 at 22:27 -0400, DJ Delorie wrote: also re-read the data sheets any chance you tied a reference output to ground? Which chips would have these? The OLED has a few pins that must remain floating and they're floating. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
can I see a bom or schematic? http://www.delorie.com/electronics/alarmclock/20070913-design.zip ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
1) Have you put a reasonable 16 ohm load across the speaker pins of U302 and U303? 2) The datasheet for TDA7056 shows a 5K resister between the input pin and ground. 3) from the dac to the speaker drivers you have an R C could you be getting a parallel inductance back through ground? Try shorting out C304 and C305 4) The gain control circuit is interesting to say the least. You might isolate its output pin and ground the signal ground to ground. Also the MPC6001 datasheet has an example of 45 degrees phase margin when driving a 500pF load. But the TDA7056 data sheet fails to mention its input capacitance. Also you gain capacitance and inductance from the MPC6001 to the speaker drivers. I might be tempted to put a small resister and a capacitor just before the speaker drivers. On Thu, 2007-09-13 at 20:08 -0700, Steve Meier wrote: can I see a bom or schematic? On Thu, 2007-09-13 at 22:27 -0400, DJ Delorie wrote: also re-read the data sheets any chance you tied a reference output to ground? Which chips would have these? The OLED has a few pins that must remain floating and they're floating. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Ok, here's a random thought. What if the hotplate reflow delaminated one of the layers? You'd still need a cause, but it would make the cause's minimum size smaller. Of course, there's no *visible* effect on the pcb from the hotplate, not even a mild yellowing on the back. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
gEDA-user: buzzing board
Ok, help me out with this one. The PCB for my alarm clock buzzes. It's really hard to tell which part is doing it, just from listening. The sound may be a combination of a high pitch whine and a 100hz buzz (the oled is 100hz). The buzzing is related to what's displayed on the OLED; the +12v to the oled has noise on it (0.5vpp) that corresponds to current draw. If I erase the screen, or run without the oled, or unplug the power jumper for it, the buzzing stops. However, adding more bypass on it (which gets rid of the noise) doesn't stop the buzzing, nor does shorting out the enabling transistor, nor bypassing the LDO. Removing the bypass cap doesn't make it worse. The OLED power supply is on the opposite end of the board (a few inches away) from the 3.3v switcher. I *think* the sound may be coming from the switching power supply (it has three power inductors in it), but neither the +15v power input nor the 3.3v rail have any noise on them (outside of the 150KHz from the switcher itself). Bypassing two of the inductors (the filter ones) does nothing. Pressing on any component does nothing. So, three questions: 1. How do you find out where such a noise is coming from, when everything is so close together? Neither a stethoscope nor a straw were helpful. 2. What kind of components *can* make that kind of noise? 3. If you know what's causing it, how do I fix it? ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Sep 13, 2007, at 12:34 AM, DJ Delorie wrote: Ok, help me out with this one. The PCB for my alarm clock buzzes. It's really hard to tell which part is doing it, just from listening. The sound may be a combination of a high pitch whine and a 100hz buzz (the oled is 100hz). The buzzing is related to what's displayed on the OLED; the +12v to the oled has noise on it (0.5vpp) that corresponds to current draw. If I erase the screen, or run without the oled, or unplug the power jumper for it, the buzzing stops. However, adding more bypass on it (which gets rid of the noise) doesn't stop the buzzing, nor does shorting out the enabling transistor, nor bypassing the LDO. Removing the bypass cap doesn't make it worse. The OLED power supply is on the opposite end of the board (a few inches away) from the 3.3v switcher. Is it convenient to try putting an choke in series with the OLED's power supply line, with the OLED's bypass capacitor on the OLED side of the choke? I *think* the sound may be coming from the switching power supply (it has three power inductors in it), but neither the +15v power input nor the 3.3v rail have any noise on them (outside of the 150KHz from the switcher itself). Bypassing two of the inductors (the filter ones) does nothing. Pressing on any component does nothing. So, three questions: 1. How do you find out where such a noise is coming from, when everything is so close together? Neither a stethoscope nor a straw were helpful. I've only used those two methods, aside from probing around with an oscilloscope to look for the noise. One other trick that I've not tried (if anyone can comment on this I'd appreciate it) is to use an inductive pickup probe to look at the *current* waveforms on the supply lines to different parts of the circuit, and see what corresponds to the noise you're hearing. 2. What kind of components *can* make that kind of noise? Inductors and PCB traces, mainly...but I suppose nearly anything probably could, to one degree or another. 3. If you know what's causing it, how do I fix it? Hot glue, molten wax, conformal coating.. -Dave -- Dave McGuire Port Charlotte, FL Farewell Ophelia, 9/22/1991 - 7/25/2007 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
DJ Delorie wrote: 1. How do you find out where such a noise is coming from, when everything is so close together? Neither a stethoscope nor a straw were helpful. Get an electret mic running off a battery on one scope lead Probe around with other scope lead to see what is in sync with it just to make sure you are looking at the right part of the circuit. You could spend ages looking at that switcher for the OLED and find out that the buzz was a slightly different frequency coming from somewehere else. Next you can get a peizo element and solder some whiskers to it and use that to probe components for the same noise. With contact from the whiskers you maybe able to track it down further than a straw/stethescope could 2. What kind of components *can* make that kind of noise? Anything from inductors and electro caps through to actual copper traces. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Is it convenient to try putting an choke in series with the OLED's power supply line, with the OLED's bypass capacitor on the OLED side of the choke? Hmmm... 100uH power inductor, no change. I've only used those two methods, aside from probing around with an oscilloscope to look for the noise. One other trick that I've not tried (if anyone can comment on this I'd appreciate it) is to use an inductive pickup probe to look at the *current* waveforms on the supply lines to different parts of the circuit, and see what corresponds to the noise you're hearing. I don't think my parallel-port scope is sensitive enough for that. Plus, anything with a coil just picks up magnetics from the switcher's inductor, but the switcher isn't the supply that provides the +12v. 2. What kind of components *can* make that kind of noise? Inductors and PCB traces, mainly...but I suppose nearly anything probably could, to one degree or another. PCB traces? 3. If you know what's causing it, how do I fix it? Hot glue, molten wax, conformal coating.. I've tried pressing on various parts of the board to no avail. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Sep 13, 2007, at 1:00 AM, andrewm wrote: 1. How do you find out where such a noise is coming from, when everything is so close together? Neither a stethoscope nor a straw were helpful. Get an electret mic running off a battery on one scope lead Probe around with other scope lead to see what is in sync with it just to make sure you are looking at the right part of the circuit. That is a DAMN good idea! I'm going to add that to my bag of tricks! -Dave -- Dave McGuire Port Charlotte, FL Farewell Ophelia, 9/22/1991 - 7/25/2007 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
On Sep 13, 2007, at 12:55 AM, DJ Delorie wrote: Is it convenient to try putting an choke in series with the OLED's power supply line, with the OLED's bypass capacitor on the OLED side of the choke? Hmmm... 100uH power inductor, no change. Crap. :-( I've only used those two methods, aside from probing around with an oscilloscope to look for the noise. One other trick that I've not tried (if anyone can comment on this I'd appreciate it) is to use an inductive pickup probe to look at the *current* waveforms on the supply lines to different parts of the circuit, and see what corresponds to the noise you're hearing. I don't think my parallel-port scope is sensitive enough for that. Plus, anything with a coil just picks up magnetics from the switcher's inductor, but the switcher isn't the supply that provides the +12v. True. :-( You might be able to temporarily shield that inductor, but that's a shot in the dark. 2. What kind of components *can* make that kind of noise? Inductors and PCB traces, mainly...but I suppose nearly anything probably could, to one degree or another. PCB traces? Yes, they can actually resonate. I know you've been working with desktop computers for a very long time (I used DJGPP in ~1992)...have you ever noticed a squealing sound coming from a machine when it's busy, changing with processor activity? Sometimes that's the power supply, but it's usually traces on the motherboard. -Dave -- Dave McGuire Port Charlotte, FL Farewell Ophelia, 9/22/1991 - 7/25/2007 ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
Get an electret mic running off a battery on one scope lead Circuit? I tried the mic+scope trick, but nothing came out of it, so I figured it needed some biasing. Probe around with other scope lead to see what is in sync with it just to make sure you are looking at the right part of the circuit. I can see the oled's image in the +12v noise, kinda like looking at a video signal through a low-pass filter, but you're right - I might not be hearing *that* signal. You could spend ages looking at that switcher for the OLED and find out that the buzz was a slightly different frequency coming from somewehere else. The OLED uses an LDO linear regulator. The switcher is for the +3.3v rail. If I pull the jumper off for the +12v to the OLED (independent circuit), or just cover the photocell so it goes to dark mode (almost no pixels on), the buzzing stops. ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
Re: gEDA-user: buzzing board
DJ - On Thu, Sep 13, 2007 at 12:34:38AM -0400, DJ Delorie wrote: It's really hard to tell which part is doing it, just from listening. The sound may be a combination of a high pitch whine and a 100hz buzz (the oled is 100hz). I *think* the sound may be coming from the switching power supply (it has three power inductors in it), but neither the +15v power input nor the 3.3v rail have any noise on them (outside of the 150KHz from the switcher itself). Bypassing two of the inductors (the filter ones) does nothing. Pressing on any component does nothing. 3. If you know what's causing it, how do I fix it? A lot of switching power supplies have a low-current mode where they don't switch at the full rate. Those modes tend to be noisier, both electrically and acoustically, than the normal fixed-frequency mode. If that's the culprit, most switching controller chips have a control pin to disable it. They don't make it the default, because it decreases efficiency. - Larry ___ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
