4049 Oscillator with Mark and Space (CB24857E)

With mark and space adjustment this circuit was found in November 1984 Radio Electronics. The base frequency depends on C1.

Stepper motor as encoder (CB21248E)
In the figure we have the way to use a stepper motor as an encoder. Operational amplifiers can be of...
Refrigerator Alar (CB1351E )
Placed inside the refrigerator, this circuit triggers an oscillator when the part is opened...
Smoke Alarm (CB13235E)
We found this circuit in an old documentation from the 70s, but it can be assembled with more...