RF and Audio Probe (CB5912E)

Any FET can be used on this 80's circuit. Power can be supplied with batteries. The output is applied to the input of a small audio amplifier.

Crystal Calibrator (CB3893E)
With the precision given by the crystal this circuit provides signals of several frequencies for the...
Slow Turn On Power Supply For Amplifiers (CIR815E)
This circuit is used to cut the “click” in the loudspeaker of amplifiers when they are turned on....
Reflected Power Adapter and Monitor CW (CB3884E)
We found this circuit in an old American documentation for hams. The circuit serves as a telegraph...