From: email@example.com (The little lost angel)
Subject: Re: How to make/solder a circuit fast?
Date: Sun, 22 Sep 2002 04:32:08 GMT
Organization: Yes please, I'm quite disorganized & lost at the moment
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NNTP-Posting-Date: Sun, 22 Sep 2002 04:30:44 +0000 (UTC)
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On 21 Sep 2002 16:42:25 -0700, email@example.com (N. Thornton) wrote:
>So no scope. Do you not have a piezo bleeper? theyre only 20 cents,
>they make horrid bleeping noises in lots of things these days, so
>they're not hard to find lying about. They're very handy for seeing
>whats going on in circuits.
I've never heard of a piezo bleeper but take it to be some kind of
speakers? Though given that the PSU's main output is switched at
something like 100Khz ~200Khz, wouldn't any noise be out of human
>PC scopes are free, as are very old PCs that will run the software. A
>486 and an old ISA sound card is all thats needed, with Win 95 or 3.1.
>95 needs 12M RAM.
hehehehe, the same reason I didn't go for a PC scope is due to the
frequency needed. These are all limited to a max of 96Khz for the best
soundcard I can find.
Unless you know where I can find a working scope for less than 100USD?
>Another way to distinguish is to see if theres a differnce between
>average fan supply V and peak V. A moving coil meter will give you
>average V. A 1k R then a diode supplying a 1uF capacitor wouild give
>you the peak voltage, which can be measured wi digital or moving coil
I only have digital scope, would it not measure average V? Is it
because digital scopes samples the voltage so it only reports what it
see at that point in time? But wouldn't this mean for a PWM signal,
the DVM would see different voltage each time?
>With a dc supply, peak V will be 0.6v below average, due to the
>diode's V drop. With PWM supply, ie a chopped dc supply, Vpeak should
>be around 12v, V ave maybe 6v.
That wouldn't be too bad right? Since I've got a 5V regulator at the
very start of the whole chain that can handle up to something like
24V~35V (sorry spec sheet somewhere else ATM).
>You can just take your chances of course, or you can test it.
I'll try to find a way to see the part number on the IC for the fan
driver (is this the correct way to use the term driver?). Just have to
figure out how without ruining the whole thing. :D