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  1. onekohm

    Help with removing tungsten oxidation

    Thanks for the thoughts, btrueblood. The back mass is indeed potted in epoxy in the end. The corrosion is a difference from before, and while it probably doesn't affect anything, I don't like it. I found some other references to using hydrogen peroxide either alone or with ammonia. The...
  2. onekohm

    Help with removing tungsten oxidation

    Hello all, hope this is the right forum to ask. We use tungsten chips from a machining operation in a back-mass. The tungsten is sieved to select the correct size (around 1 mm), cleaned in an ultrasonic cleaner with hot water and degreaser several times, rinsed with water and finally MEK...
  3. onekohm

    Clean DC from wildly varying AC

    Thanks again for your help. I'll mull it over over the next few days. If the info I get from the actual magneto differs by much I'll get back to you with some new numbers. Until then, Happy New Year everyone.
  4. onekohm

    Clean DC from wildly varying AC

    Gunnar, you've hit my biggest problem right on the head. I was hoping using a SMPS with 4-60 volt input would allow the zener, as I would only have to clip above 60 V. Is there a better method? The low end is a problem. I haven't checked output of the exact magneto, but a very similar...
  5. onekohm

    Clean DC from wildly varying AC

    Thanks for your suggestions. I've been reading buck data sheets, and I will still need something to clamp the voltage peaks from the rectifier. So far the highest allowed input voltage I've found with the output I'm looking for is 60V. Is zener and emitter follower good for this, or do you...
  6. onekohm

    Clean DC from wildly varying AC

    Hello all, I have a pet project that is giving me a headache. I am trying to power a microcontroller circuit from a magneto. The magneto is an AC source which varies in frequency from about 2 to 40 kHz. Waveform is very roughly sinusoidal, with peak voltage varying from about 8 to over 100...
  7. onekohm

    Low voltage inrush current limit

    Thanks Glen. I've just skimmed the ap note for now, but I'll be reading deeper into it tonight. Has potential, I like the low part count.
  8. onekohm

    Low voltage inrush current limit

    Yes, I think the problem is caps. Mostly on the supply to a switcher that puts out +/-15 Vdc from the 5 V. I could try dropping the values, what's on the board is what the datasheet for the switcher called for. IRstuff, the voltage drop under normal conditions is exactly the problem with...
  9. onekohm

    Low voltage inrush current limit

    Sorry, this is a fix to an existing board. In a small box with little room to add to the fun. There could be a redesign in the future, but how would you "design out the surge"? I thought that a common way of doing this is with PTC thermistors.
  10. onekohm

    Low voltage inrush current limit

    Hello everyone. I have a circuit which runs at 5V, ~330mA usually. At turn-on I have a spike to above 2A for a short time (on the order of miliseconds, not sure right now exactly how long). I would like to limit this to < 1A. The circuit is supplied by USB, and as it is now it doesn't work...

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