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.
The critical point in this 2005 project is the adjustment of the optical system, mainly to avoid...
This simple SCR trigger was found in a 1965 General Electric SCR manual. The circuit makes use of a...
We found this circuit in a 1976 technical documentation, but it can be assembled with modern...