Modulator Amplifier (V1574E)

This circuit is from a 1938 tube manual. Transformers are the critical components. Component values are given.

Signal Injector (CB5889E)
This simple injector circuit can actually be powered by voltages from 3 to 9 V. The frequency is...
Simple Timer Using the 555 (MSB123E)
This simple timer can be used in many applications such as egg timer. The LED glows up when S1 is...
CMOS Touch Key with Lock (CB1275E)
This circuit locks after a short touch on the sensor. The circuit can be powered by voltages from 5...