Receiver for the 10-meter range (CB20518E)

Found in a book on transistors from the 50's. This receiver is very sensitive and features loudspeaker reproduction. Transistors are from the time.

Instrumentation Amplifier (CB4928E)
This circuit makes use of older operational amplifiers, but can be designed on the basis of modern...
555 Sequencer (CB3981E)
This circuit generates sequence of pulses in order and times determined by the capacitors in pins...
Doorbell 555 (CB4756E)
This circuit was found in an old Poptronics but is still current as transistors can be replaced...