Re: "Fizzing" power supply.
- From: Pete Verdon <usenet@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Tue, 12 Feb 2008 00:55:56 +0000
Tim Wescott wrote:
Try a six ohm (or so), 2 watt resistor in parallel with the coil. IfI forgot to mention -- try it with just resistors, enough to draw the same current at the same voltage (6 ohms at two watts). If it _still_ fizzes then you've bought a cheapo power supply.
that stops the 'fizzing' then the supply is oscillating because of the
inductive load. If it works, then you can put a big capacitor (I don't
know what to recommend, but I'd start with 1000uF, observing polarity)
in series with the resistor, which can now be reduced to a 1/4 watt
device.
Unfortunately I don't have anything like those values in my parts box. However, I tried shorting it out briefly (a bench supply ought to cope with the occasional misconnection, right?) with both plain wire and then with a 100kO (I think) resistor. Neither fizzed, which I assume means that the noise wasn't due to overload (as someone else suggested).
Hopefully given the name of the newsgroup my near-total lack of electronic knowledge is not going to be too much of an embarassment :-)
Pete
.
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