DIY Analog to Digital Converter Using OPAMPS

Other Hardware Sensors
1

So here's the situation:

  1. I have 8051 that I want to use but it doesn't have its own ADC
  2. I have a lot of quad opamps.
  3. I want to convert the loudness of a piezo sensor to MIDI velocity so fidelity is not that important.

Is there a way I can use OPAMPS as 8bit ADC?

2

Op Amps don't output a serial data stream, so not really.
You'd have to create a sample & hold circuit, then make a series of comparators that would be high or low based on increasingly smaller comparisons of voltage level. And then read in the output of each of those comparators.

Serial ADCs are pretty common, can do all that in single package:
http://www.digikey.com/product-detail/en/TLC549CP/296-1853-5-ND/277498

http://www.digikey.com/product-search/en/integrated-circuits-ics/data-acquisition-analog-to-digital-converters-adc/2556291?k=adc

3

Use the op amps to make a flash converter:-

I want to convert the loudness of a piezo sensor to .....

Just a simple A/D will not give you a loudness measurement, you need a peak detector before it.

I have 8051

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