This circuit, obtained from a 1965 magazine, can still be assembled using some modern equivalent components. The transistors may be BC558 and the transformer is obtained from a disused transistor radio.
This simple calibration circuit consists of a crystal oscillator that generates an accurate 100 kHz...
This configuration is suggested by Mullard (Philips) in an old manual of 555 integrated circuits....
This crystal oscillator is indicated for the calibration of IF steps of common radio receivers. The...