Crystal Tester (T329E)

This circuit is from a 1964 publication. The circuit tests crystals from 2 to 20 MHz with good accuracy. The power supply is included.

Monostable with input lock (CB5426E)
This circuit is from an old manual, but can be easily assembled as the integrated one is still...
Blown Fuse Alarm (CB6109E)
We found this circuit in a 1967 Electronic design. However, it can be easily implemented even...
Low input current adder (CB4908E)
This circuit has a 200 kHz bandwidth and a low input current. The circuit is from the 80's, but...