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Posts posted by jgeidl

  1. Thanks Guys.

    I don't pretend to understand how you  get from 19 VAC to 24VDC through rectification but will assume that to be true.  Modifying the transformer is really not a practical possibility.  These transformers are from UPSs so I am wondering how they do it; they provide the power to keep the internal battery charged.  I may have to go to plan B...Oh, wait, I don't have a plan B. :-)

    How about a big honkin' Zener diode after the rectifiers and before the voltage regualtor?


  2. Basil,

    You might want to take a look at the stuff this guy sells related to PICAXE.  He has chips but, more importantly, he has prototyping boards that have a serial hookup and power supply on them so all you have to do is plug in the chip and program it.  I have bought several things from him and he seems to be a good guy.  Besides that, he is cheaper than the "official" US distributor for PICAXE.


  3. I have been following this thread to see the outcome.  One thing, based on th elast drawing, that should be noted is that you are not working with 20 LED/resistor combinations in series, you are working with 20 LED/resistor combinations in parallel so you might want to rework the numbers a little.

    I am also really happy to see the transformer get into play.  Runnig this circuit without a transformer is just asking for someone to get hurt real bad, as AG has pointed out earlier and repeatedly.

    As to cost, I can't help but wonder if a 12VDC wall-wort transformer and, maybe,  a 7805 wouldn't be a quick, easy and cheaper solution to building the power supply cicuit.  Even better would be 6VDC wall-wort.

    Just some thoughts...


  4. If you can tolerate a little more than 0V on the bottom end and a little less than 30V on the top end AND you don't have a burning dsire to build the whole thing yourself you might want to take a look at these power regulators on eBay: 250068727100 .  I have used these several times and been very pleased with the results.


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