[sdiy] is this PSU OK?

[Happy Harry]

Do you have a dual trace scope... are both channels ON ???

Try using one channel only... The scope may be set to chop mode
and it is bouncing from channel to channel...

But every 3mS for this chop would normally be WAY too slow. Usually
you could only see chopping at very fast sweep speeds.

Do you have a 10X sweep switch ??  It might be .5mS you are looking at

Notice... I'm suspecting your test equipment here rather than the circuit. 
You need to convince yourself that this signal is real...

Try looking at some other, known signals like the probe cal output
of the scope.

With the AC coupling you could see ripple and noise... It sounds like your 
ripple and noise are VERY low, if the measurement is correct.

Once you switch to DC, you will probably have to be at maybe 2V to 5V
per division to see the "whole" signal.

If you set the vertical gain higher, the signal should blow right off the 
screen.

H^)  harry

PS : are you SURE you wanna tie the mains ground to the 0VDC point ?
I'd do that later (maybe much later)



>From: ElmacacoX at aol.com
>To: synth-diy at dropmix.xs4all.nl
>Subject: [sdiy] is this PSU OK?
>Date: Fri, 24 Aug 2001 14:03:43 EDT
>
>Hi Everybody,
>
>I am looking at a power supply I made on the scope, and I am not sure if it
>is working right.
>
>I have the settings at 5ms /cm and .01 volts/CM, when AC coupled I get what
>looks like noise that ranges about one fifth of one cm, so .0020V, when DC
>coupled I get what looks like a straight line that is kind of dotted, every
>3ms there is a little gap, and it looks like the trace is shooting upward 
>vey
>quickly at these gaps and they appear to shoot up to the top of the screen.
>but when I change the volt/div settings to chase itand see how far it 
>spikes,
>it becomes a solid bar, but it is still present when changing the time
>settings.
>
>
>
>the power supply is basically like this,
>
>         ----------------
>---------------4700uf--1000uf-100nF--317---10uFelco--100nF
>[24VCT at 1.25A]  4x 4001 rect,diodes
>        -----------------
>----------------4700uf--1000uf-100nF--337--10uF elco-100nF
>
>
>the first three caps are electolytic as is the 10uF at the end.
>I am thinking that maybe the 10uf is too big to be at the end like that, 
>but
>the schemo I got it from had them.
>I have all the caps and stuff wired correctly the PS works, giving out +/-
>12.3V,
>although I don't have the mains ground wired to the secondary 0v yet.
>
>what mai doin wrong?
>
>thanks
>
>Ed


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