Two-input amplifier (CB21661E)

The critical component of this 1967 amplifier is the driver transformer. The circuit has both high and low impedance input.

Telephone Bell (CB25683E)
This additional bell circuit was found in the February 1994 Electronics Now magazine. The...
Delayed Reed Relay (CB12185E)
A delay of a few seconds to a few tens of seconds can be achieved with this circuit found in a...
Single Transistor Alarm Circuit (CB24372E)
This circuit uses a transistor to trigger the alarm from a low quiescent current sensor. The relay...