This crystal tester was found on a 90s Ham Radio. Transistors are commonly used. The circuit is for testing crystals from 2 to 20 MHz.
This circuit is recommended for alarm systems since it has a good output stage. The circuit is...
) Suggested by Philips in a 1968 documentation this circuit has very high 10 ohm on-load voltage...
No information is given about the transformers in this circuit suggested by Motorola in a 1968...