Crystal variable oscillator (CB9506E)

Found in Radio Electronics from the 90s, this circuit can vary the frequency in small values around the crystal frequency.

Battery Status Indicator LM10 (CB14324E)
The integrated circuit used in this project is not common today, but the circuit can be adapted to use a...
Low Current Source (CB20199E)
This low current source without a transformer is intended for applications where insulation is not...
830 W Dimmer (CB7185E)
This dimmer for high-powered incandescent lamps was found in a 1967 General Electric manual. The...