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 generates noise pulses for audio equipment probes. The circuit is from a 90’s 303...
Originally this 2000 circuit was designed to be a switch to the parallel port, but with 5 V or...
This small inverter that produces high voltage from a 6 V source was found in an American...