We found this time base of 0.1 to 90 seconds in a circuit manual from the 90s. The single-use transistors used are common and the frequencies given by the adjustment by the potentiometer.
This amplifier circuit for the 7 MHz band, which corresponds to the 40-meter band of radio...
This high-power circuit from a Popular Electronics of the 80's makes use of common SCRs that admit...
This circuit is from an American documentation from 1975. The single junction transistors can be...