Found in an American publication from 1968, this circuit generates pulses at a rate of 2,500 per second. The transistor can be replaced by a modern equivalent.
An integrated circuit 741 (operational amplifier is the basis of this voltage indicator, which can also...
This SCR circuit was found in an American 1980s documentation. The circuit is still current,...
With this circuit it is possible to use a frequency meter as a tachometer. The circuit was found in...