Blocking Oscillator (CB21815E)

We found this circuit in the 1960 Mullard transistor manual. The transistor is made of germanium.

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Complex Sound Generator (CB16437E)
We found this circuit in a 1987 documentation, but it can still be easily assembled. Its output must...
Fire siren (CB21232E)
This circuit that emits siren sound can be used in a fire alarm. We found it in an old American...
Simple Alarm with SCR (CB24114E)
Found elsewhere in this section, this circuit is from the April 1971 Radio Electronics magazine. Note...