This circuit was found in a 1967 Electronic Design. The circuit makes use of components from the time. Modern equivalents can be used.
I found this circuit in a 1986 English magazine. It can still be easily assembled, exchanging Q1...
We found this circuit in an Argentine publication from the 70s. The coil can be made with 80 turns...
Found in General Electric documentation from 1967, this circuit makes use of an unusual...