This 6-transistor circuit had excellent sensitivity using germanium transistors. The push-pull stage used two transformers, one drive and one output as we usually find at 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...