This circuit is one of many that the reader can find in this section for testing crystals. The circuit uses an indicator LED. Transistor Q1 determines the maximum crystal frequency that can be tested.
This circuit makes use of a mechanical delay line to produce the reverberation effect. This is a...
This circuit was found in an American documentation from 1975. The components of the time can no...
The oscillator circuit is an ICM7556, the dual CMOS version of the 555. The frequency depends on...