Scott shows you how to modify a PC sound card to allow D.C. voltage measurements, he writes –
A PC Sound Card typically contains a sixteen bit ADC (or two if capable of capturing in stereo) which is used to digitise A.C. signals in the audio frequency range. In its typical audio application the ADC is intentionally isolated from any D.C. applied to input ports by series capacitance and so cannot be used to capture D.C. This page describes a general method for modifying a PC sound card to permit the digitisation of D.C. signal levels allowing a sound card’s ADC to be used as the basis of a simple and accurate ground referred voltmeter with millivolt or better resolution.
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2 thoughts on “HOW TO – Modify a PC sound card to allow D.C. voltage measurements”
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Not so easy.There are internal filters to sample 20Hz-40KHz signals only.You can remove that dc capacitor,but not the intenal ones used to built that filters.So you need sampling above 20Hz at least