LM3900 Amplifier (CB25165E)

This circuit with Norton operation is from an article in Radio Electronics magazine. The gain is given by the resistors.

Motorcycle Timed Alarm (CB16869E)
This circuit can use a pendulum sensor. We found this configuration in a 1994 publication. The...
Photoelectric alarm (CB8337E)
This circuit is from a 1964 Electronic Design. The sensor is an LDR and the transistors are...
Preamplifier and Vox II (CB19993E)
This circuit works both as a preamplifier and activates a relay when speaking in front of the...