Latching relay (CB25722E)

The figure shows how to connect a relay to obtain the latch effect. The circuit is from an Electronics Now from June 1994.

Comparator With Op. Amp. (MSB069E)
This simulation shows how to use an operational amplifier as a voltage comparator. The sample uses the...
Telephone Conversations Automatic Recording (CB17296E)
This circuit automatically activates the relay when the phone is answered, closing the record...
Vehicle Alarm (CB4867E)
This car alarm was found in an American '80s documentation. The circuit automatically activates...