Motorcycle headlight monitor (CB9117E)

This simple circuit was found in Popular Electronics from the 1980s. The circuit uses an LED as an indicator.

Very High Voltage generator (CB15714E)
This circuit generates voltages of tens of thousands of volts for projects such as electrostatic filters...
Resistor voltage control (CB20758E)
This circuit was found in an old American documentation. The operational used is of the...
NiCad Charger (CB15654E)
Rechargeable Nicad batteries type AA, C or D can be recharged with this circuit, which is nothing...