| On Nov 18, 3:31 pm, Imbanon <[email protected]> wrote:
|
| I can't test the inductors, but they should be 100uH, 1watt max....
| The diodes are UF4004. I suppose they should work..
|
| Can I use some other inductor, like 220uH?
Are using the parts provided by that kit, or are you just using the
schematic ? This is very important for us to know !
Not all inductors are the are same. 1W ?. That's not a typical
inductor rating. Its usually current (amps, milliamps), for maximum DC
current, and/or maximum saturation current. A supply like this should
be able to handle 500mA (half amp), at the very minimum. Any old pile
of crap from your junk bin just won't do.
Make sure its a UF4004, and not to be confused with a 1N4004. The "UF"
means its an "ultra fast" switching rectifier, in the ballpark of 50
to 100nS (10^-9sec). A 1N4004 ("jelly bean" rectifier) switches much
slower by orders of magnitude. An "order of magnitude" is equal to
10x, 2 orders = 100x, ...
The inductance isn't super critical. What is critical, is that it can
handle the current. Use power inductors.
If you have a scope, test the frequency first. Just hook up the 555,
but leave off the FET and coil, and the feedback parts going back to
pin-5. Leave pin-5 disconnected from everything. Turn it ON, and check
the frequency at pin-3. It calculates to 31KHz, with the schematic's
part values. See if its in the ballpark of 30KHz (20KHz to 40KHz). If
one of those parts is too big, then the frequency will be too low, the
symptoms you describe will happen..
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