We found this circuit in a 1976 publication. The transistors can be BC547 or 2N2222. Crystals up to a few tens of Megahertz can be tested. The LED can be of any type. The capacitors must all be ceramic.
This circuit is used to test capacitors with a working voltage above 150 V, detecting shorts or...
The circuit shown is used to reset TTL logic when power is established. The circuit uses a 7413...
This circuit was obtained in a Motorola manual from the 70s. The integrated circuit is from that...