Door buzzer or alarm (CB20492E)

This solar powered circuit was found in a 1991 documentation. The transistor is a general purpose NPN.

Supply for photo multiplier tube (CB8123E)
Found in a magazine 73 for radio amateurs of the 90s, this circuit shows how to supply a photo...
RGB to NTSC Converter (CB26154E)
This circuit was found in the 1991 Electronics Experimenters handbook. It can be used to display RGB...
Zener Regulated Wien Oscillator (CB14907E)
This sinusoidal oscillator was found in Radio Electronics in 1989. It uses a 741, but other...