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.
The purpose of this circuit is to send signals on low impedance lines with a maximum voltage of 70...
This circuit, from a 1977 publication, allows to know if a bipolar transistor of general use is...
We found this circuit in an old English documentation from the 70s. The transistor can be a modern...