This circuit was found in a Popular Electronics from the 90's. The output signal can be applied to a headphone or speaker. The microphone can be a piezoelectric tweeter capsule or other type.
This non-regulated power supply uses a single secondary winding transformer. The secondary voltage...
Using a small incandescent bulb as a regulator, this Wien bridge oscillator produces a sinusoidal...
The figure presents a configuration that can be very useful for audio equipment designers. What...