On Sun, 30 Nov 2008 21:57:41 -0600 Kipton Moravec <[EMAIL PROTECTED]> wrote:
> I probably would have gone with the Atmel Data Flash as opposed to the > memory chips you are using. (But it uses SPI Interface.) For example: > http://www.atmel.com/dyn/resources/prod_documents/doc3500.pdf > > > As far as the Power Supply goes, replace the 470 pF cap. Either you > accidentally put the wrong on on, or something is bad with the solder > joint. Take what you have off, and put a new one on. Clean the board > with Alcohol if you are using no clean or rosin core solder, or wash > it if you are using water soluble solder flux. Thanks. I replaced the cap, and it has the same effect. However, one of my friend pointed out, that the regulator I am using maintains its switching frequency as a function of the output current. The consumption is low. > The other problem may be the C101 470 uF capacitor. Usually switchers > need very low ESR capacitors in this position. So two electrolytic in > parallel, or a Low ESR Tant. and add a ceramic 10 uF and 1 uF help > ensure a low ESR with the big cap. That is a good point. Thank you. > Kip > > On Sun, 2008-11-30 at 18:18 +0100, Levente Kovacs wrote: > > Hi, > > > > > > In the last few weeks, I've been busy designing and bulding a > > temperature sensor/logger. The second version is out and can be > > found here. > > > > http://logonex.eu/~leva/projects/temp_collector/ > > > > There are a few pictures of it. > > > > http://logonex.eu/gallery/tns/1043.html > > > > There is no firmware yet, I am planning to write it in the coming > > week. > > > > Originally, I was asked to make some temperature logger, which logs > > the data of samples taken every half 30 minutes in a half of a > > year. I planned using KTY temperature sensors. However, if you > > change the gain of the INAs you can use it with PT100 sensors. I am > > planning to replace my reflow oven design with this circuit. BTW > > INA. I know that one can buy INA in a single IC, but, AFAIK they > > are quite expensive, and they are too sophisticated for this > > application. > > > > It is equipped with I2C eeproms to store the recorded data. The RTC > > with the supercap maintains time and date data even with power > > supply loss. I am thinking to use a battery instead of the supercap. > > > > The power supply gives me lot's of head scratching. I placed a > > 470pF capacitor to produce the 50kHz switch frequency, but > > according to my measurements it is only 6kHz. I replaced the cap, > > but stiill the frequency is low. Despite this fact, it is working > > good, and it has only 30mV ripple. If anyone could give me a hint > > what is going on here, that would be fine. In my first sample, I > > used the same circuit, with the same cap, and the frequency was > > 50kHz. Very odd. > > > > > > Cheers, > > > -- > Kipton Moravec AE5IB > "Always do right; this will gratify some people and astonish the > rest." > --Mark Twain > > > > > _______________________________________________ > geda-user mailing list > geda-user@moria.seul.org > http://www.seul.org/cgi-bin/mailman/listinfo/geda-user > -- Levente Kovacs http://logonex.eu _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user