test bench was Re: Old 486 Board for ECU? Why?

[Tom Parker]

Frederic Breitwieser <frederic at xephic.dynip.com> wrote:

>Sound cards have a DAC, two in fact, one for each channel.  You can
>multiplex these using a CD4066 chip and a simple circuit to select which
>one.  The 4066 is a CMOS controlled analog switch.  I've used them in audio
>circuits, specifically homemade guitar effects as a way of bypassing the
>effect, or not.  Would work here too.

>But, I never tried to use the SB DAC to convert signals from an analog
>voltage source such as a sensor.  I believe teh DAC is good from 0-1V, which
>might be fine for an O2 sensor (theoretically), but for a MAF 0-5V, the
>range must be scaled down through an op-amp, which might decrease accuracy.

They are indeed a good, however I very much doubt you can read DC voltages
with one. I think they are only good down to 20Hz or so. They have series
capacators in them which will prevent you from measuring a static signal and
will give very weird results from a slowly changing one.


You might be able to follow the signal path on the card and remove the
capacators... maybe.

--
Tom Parker - parkert at ihug.co.nz
           - http://www.geocities.com/MotorCity/Track/8381/

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