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 intended to match impedances for observing signals on an oscilloscope. The FET...
The battery is charged by the photocell that keeps the low consumption beacon in the dark. The...
This is the configuration suggested by National Semiconductor for cascading the LM12. The LM12...