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 amplifier was found in a Japanese publication in 1972. Transistors are uncommon today, and...
The current of this source is 200 mA at the most, and the output depends on the zener that may...
Found in Mallory documentation from 1968 this circuit uses an integrated circuit from that time. The...