From: email@example.com (Bob Masta)
Subject: Re: How to make/solder a circuit fast?
Organization: Interstellar Research
References: <firstname.lastname@example.org> <email@example.com> <3D864834.firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org> <email@example.com>
X-Newsreader: Forte Free Agent 1.11/32.235
Date: Thu, 26 Sep 2002 12:43:18 GMT
NNTP-Posting-Date: Thu, 26 Sep 2002 08:43:21 EDT
On Wed, 25 Sep 2002 16:02:56 GMT,
firstname.lastname@example.org (The little lost angel) wrote:
>On Wed, 25 Sep 2002 11:50:03 GMT, email@example.com (Bob Masta) wrote:
>>Just out of curiosity, I'd be interested in what your hobby project
>>entails and what sort of DAQ systems you are interested in.
>>I'm in the process of converting my DOS-based Daqarta software
>>to Windows, and I'd like to make it as useful as possible.
>Hehee, it's the same old project I started I think almost two years
>back? Maybe I'll never get it completed but I like the fact I've
>learnt a lot of things I would never have picked up.
>My friend inspired the idea, but he's too busy to bring it to fruition
>so I'm the one doing the groundwork for now.
>The project involves loading a SMPS with a variable resistive load
>(after the non-response trying to get high power resistors, I'm most
>likely going with power mosfets).
>The spec allows for as low as 50mV ripple and noise, so the scope has
>to be able to pick that up at 3.3V to 12V range. And it's defined as
>within the band of 10Hz to 20Mhz
>Plus the SMPS must remain stable under rapid load changing conditions
>up to 10Khz.
>I don't care about real time, as the data has to be captured over an
>extended testing period with variable loads, then ran through a
>But a sound card at best gives me 48Khz (I can't get the 96Khz sound
>card), not good enough for noise/ripple analysis but for others pretty
>okay. But was in order to use 12V on the sound card is a problem. The
>spec allows it to 10.80 to 13.2 range. I haven't figure out a way to
>reduce 13.2V to a range acceptable by the soundcard without killing
>any 50mV spikes I'm interested in catching.
Can't help with the slow sample rates on sound cards,
but the level issue should be no problem. Consider that
50 mV is only 48 dB down from 12 V, which is 8 bits
(6 dB per bit). 16-bit sound cards should be able to handle
this easily, even rather cheap ones. Use the Line input,
not the Mic input, for best signal /noise ratio.
But note that sound cards don't go down to DC anyway.
If you don't really need to measure the DC here, just
the trash, then you may not need to attenuate the input
much anyway, just enough to keep the noise peaks under
1 V or so (or whatever your sound card limit is). The DC
will be blocked by the input capacitor on the sound card.
Certainly worth a look with whatever sound card you have
D A Q A R T A
Data AcQuisition And Real-Time Analysis
Shareware from Interstellar Research