In Reply to: very basic opamp amplifier posted by Corry Lazarowitz on 06/23/02 at 3:14 AM:
A few clarifications:
1. Specify the OPAMP used.
2. Specify the type of mic used (or expected input signal level), and its output impedance.
3. Specify the required gain.
1. The AT power supply generally supplies +12V (among other output voltags). You cannot use a linear (I assume) 12V regulator with +12V input. The regulator requires an input of at least +15VDC in order to regulate down to +12 (even LDO's require more than +12V input).
2. If you are using an opamp with single supply, you should bias one of the inputs with a resistive divider such that the output is sitting a about half Vcc (around 6V) for maximum dynamic range, and then AC couple both input and output.
Hope that helps,