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 more sensitive than the previous one, in the sense that we can use weaker and more...
This 3-transistor timer was found in the January 1994 issue of Electronics Now magazine. The...
This circuit appears in other articles in this section, but it is very interesting. It is a...