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.
We found this transmitter in 1980s documentation. Coil data is found next to the diagram and...
The 4528 is a dual-retriggerable monostable that needs only the timing network formed by R and C...
This circuit for analog TV was found in a 90s EDN. The integrated circuits used are from that time...