Telephone Busy Indicator (CB24430E)

This circuit for analog telephones from the 90s was found in documentation from the time. It lights up a remote LED when the extension is in use.

| Clique na imagem para ampliar |

Thermometer Using a Diode (CB382E)
The sensor in this circuit is a BA315 diode. Other diodes can be experimented, but this is one...
AND gate with LM3900 (CB25173E)
The figure shows how to implement the AND function with a Norton LM3900 operational amplifier. The number of...
High Power Oscillator (CB13126E)
A single high-power transistor MJ15003 is used in the circuit in the figure to generate strong...