[neonixie-l] Re: How can i fix this proteus bug?
I dont use proteus for simulations; strictly Verilog and SPICE. But I think I have an idea what the problem might be. I suspect the simulator is getting confused about the series resistors. When I model resistors in verilog, I *usually* use rtran statements [OK, technically it's tranif1 because I need to have a way to enable/disable the resistor]. But that becomes a problem when 2 or more resistors are in-series. In that case, I will model one of my resistors as either a pulldown or a pullup and fortunately that seems to work most of the time when I have resistors involved in a digital-only section of the design, such as a voltage-divider or a pullup resistor for a DIPswitch. So the resistor-model for digital simulations is basically open (default), weak pulldown, weak pullup, or rtran. Of course, when it comes to modeling in SPICE, nothing needs to be done because that's a purely analog simulator. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/2d595a46-dc41-42f0-ab8d-c5fbd7e602b7%40googlegroups.com.
[neonixie-l] Re: Input voltage protection
For filament protection on my NIMO project, I use individual 250mA fuses; the tube's filaments are rated for 200mA. The filaments require 1.1V, so I use a series dropping resistor and run them from a 2.5VAC transformer. This also reduces the inrush current-surge and that is the main reason why filaments fail. I also have a small FPGA that monitors the fuses, filaments and series resistors for burnout; software can query that at any time. The one flaw in my particular design is that it does not directly identify when parallel filaments burn-out. To do that I would need to monitor filament voltage and current, and my present design doesn't support that. Instead, I will have software monitor the total anode current of all tubes and by sequencing the tubes I can measure each one independently and infer when a filament is partially burned-out. This design was a bit more complex because I had to have a programmable DC offset for the filaments (I have a DAC for that). An upcoming project with jumbo 7-segment VFD's and multiple parallel filaments will require a different approach, and I do intend to monitor and control the current & voltage for each individual tube. At least with this project, I dont need DC offset. The ADC is use is a 16-channel MAX11632; it has a serial interface for programming and readback. If you've never used an ADC before, get ready to learn a lot and do some debugging; I've solved a lot of subtle issues. Now that I'm familiar with it and it's quirks, I'll likely stay with it. I use a Raspberry Pi Zero-W for control because is has built-in WiFi and runs the whole Linux stack, for $10 US. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/e81808f8-2975-4e5c-8ec6-b628f511b5de%40googlegroups.com.
[neonixie-l] Re: Input voltage protection
> Is input protection worth $5 in parts? For me, it varies with the cost of > the components at risk, complexity to rework or repair, probability of > abuse... > Forgot what may be the most important consideration... Am I repairing a board for my personal use, or is the board going to a user! It's worth a lot to me that a user never see a failure. Never. :-) -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/f92bd770-3184-4ad7-a6b0-468f2b5eb2d3%40googlegroups.com.
[neonixie-l] Re: Input voltage protection
Forgot to mention on the ADC. I also use the Arduino ADC for many projects - especially when I need multiple channels ground referenced. Include an LM4040 4.096V +-0.5% reference on one of the inputs and you can get quite good absolute accuracy if that's also needed. There are lower voltage reference parts if you're running a 3.3V system. (DigiKey LM4040CYM3-4.1-TR $0.33/ea) On Thursday, September 12, 2019 at 6:39:25 AM UTC-7, Robert L wrote: > > Here are a few parts I use on a routine basis... > > I2C digital pot - 10K shown, comes in other values: AD5259BRMZ10-R7 > (DigiKey: AD5259BRMZ10-R7CT-ND $2.85/ea) > I2C 16-bit ADC: MCP3425A0T-E/CH (DigiKey: MCP3425A0T-E/CHCT-ND > $2.24/ea) > I2C Isolator... float an ADC or other I2C parts at 200 VDC? ISO1540 > (DigiKey: 296-34871-1-ND $4.80/ea) > > Caution on the ISO1540... it is not symmetrical in that the "2" side can > handle more capacitive load than the "1" side. > Did I mention I don't like manual set trim pots? > > Is input protection worth $5 in parts? For me, it varies with the cost of > the components at risk, complexity to rework or repair, probability of > abuse... Most of my boards just have a PTC fuse, ESD and EMC mitigation. > Some have current limiting high side switches. Only the controller has the > full protection treatment. A fuse and ESD clamp are the bare minimum I'll > use. > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/9235fa97-93a1-4526-8b12-13523b6e0156%40googlegroups.com.
[neonixie-l] Re: Input voltage protection
Here are a few parts I use on a routine basis... I2C digital pot - 10K shown, comes in other values: AD5259BRMZ10-R7 (DigiKey: AD5259BRMZ10-R7CT-ND $2.85/ea) I2C 16-bit ADC: MCP3425A0T-E/CH (DigiKey: MCP3425A0T-E/CHCT-ND $2.24/ea) I2C Isolator... float an ADC or other I2C parts at 200 VDC? ISO1540 (DigiKey: 296-34871-1-ND $4.80/ea) Caution on the ISO1540... it is not symmetrical in that the "2" side can handle more capacitive load than the "1" side. Did I mention I don't like manual set trim pots? Is input protection worth $5 in parts? For me, it varies with the cost of the components at risk, complexity to rework or repair, probability of abuse... Most of my boards just have a PTC fuse, ESD and EMC mitigation. Some have current limiting high side switches. Only the controller has the full protection treatment. A fuse and ESD clamp are the bare minimum I'll use. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/486852a1-c70f-4abd-b4d8-f3b63cb4b30d%40googlegroups.com.
Re: [neonixie-l] Input voltage protection
Do you have a suggestion on an A/D IC? Or are you using one from the uC directly? I'm looking to sprinkle some A/D everywhere for my nixie and non nixie projects just for fun. On Tuesday, 10 September 2019 15:51:18 UTC-4, gregebert wrote: > > My current clock went a bit overboard with self-checking; I have A/D > converters on all supplies and software periodically monitors them for > out-of-tolerance, and will shut-down the HV if that happens > Also on a similar but separate note, anyone have a suggestion on how to protect the filament (~1V) for VFD tubes? I'm always scared my buck converter will fail and pass Vin through the filament of my harder to fine VFDs. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/dd3da112-2da4-446f-ba2e-433dbefbd891%40googlegroups.com.
