This old 1 W audio amplifier transistor circuit is from a 1967 Japanese magazine. The transistors are germanium of the time and the type transformers found in similar equipment of the time.
This circuit can generate signals in the range from 1 to 20 kHz, depending on the crystal. The...
The basis of this circuit is an LM380 that drives a speaker that emits sound when moisture is...
Using the ICM7555, CMOS version of the 555, this circuit produces a 1 kHz signal. The circuit has...