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 |

ELF Monitor (CB21055E)
This circuit monitors extra-low frequency (ELF) fields. We found it in an American documentation from the...
Controlled Oscillator (CB12682E)
We can use any type of resistive transducer with central resistance in the range of 10 k ohms to 1...
Triac Double Dimmer (CB16915E)
This circuit controls two lamps so that when one increases in brightness the other decreases. The...