In use telephone indicator (CB9297E)

Found in a Popular Electronics from the 90's, this circuit is used to indicate the operation of telephones of the time. The circuit is TTL.

| Clique na imagem para ampliar |

Audio Visual Thermometer (CB18469E)
This circuit was found in a 1974 publication. It provides a tone indication of the temperature sensed by...
DC Motor Speed Control (CB17401E)
This is a simple rheostat circuit for motor control that works with voltages from 6 to 12 V. The...
1 MHz Colpitts Clock (CB6469E)
This circuit with TTL compatible output was found in a 1968 US documentation. The circuit is...