On 18 Mag, 09:06, mattyg1...@[EMAIL PROTECTED]
wrote:
> i need to measure a low frequency waveform from a DC circuit (voltage
> up to 200mV). I need a sample rate of around 10Hz. to buy an
> oscilloscope for this is a total overkill. I was thinking of using the
> soundcard, but then realised it's AC coupled. any suggestions on a
> cheap method to find this measurement?
you could use your sound card chopping the incoming signal with a
fixed frequency of 10kHz or so, by means of a cmos switch such as the
CD4066 (if you need precision, it is better you use one DG411 or one
next generation switches with lower RDon resistance).
To achieve a good switched signal place one switch in series and one
in parallel to the sound card input, and drive the second one with the
logic complement of the first.
Bye,
Massimo
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