Found on an 80's Radio Electronics, this circuit is designed to pass the 300 to 34,000 Hz voice range using standard operational amplifiers.
This high impedance step suggested by an English publication can operate up to 1 MHz with 1 V rms...
This small audio amplifier uses germanium transistors and a 12 V supply. The circuit is from a...
Figure bellow shows another configuratíon for a Iow-frequency sine wave oscillator using CMOS...