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 can be used with 3 receivers and is intended for low frequencies (medium wave range). We...
Using two of the 4 NAND gates of the integrated 4001, the circuit in the figure activates the...
This circuit allows you to superimpose the signal from the microphone to that of the music with...