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.
This Salen-Key filter can use any operational amplifier and other frequencies can be obtained by...
Found in a 1969 documentation, this circuit is reset by a push button. The activation time is 100...
The idea of this circuit is to use an AM radio with headphones to receive sound signals...