Off-hook Telephone Indicator (CB5994E)

This circuit was found in a 1980s US publication. It indicates when the phone is off-hook by triggering an indicator.

| Clique na imagem para ampliar |

Nicad Charger for car (CB4792E)
This circuit was found in a Popular Electronics of the 90s. The resistor R4 determines the load...
2 to 6 W amplifier (CB8305E)
Obtained from a 1980s Signetics documentation, this circuit uses a common integrated circuit at the...
Digitally Controlled Filter (CB14368E)
We found this circuit in the Linear Applications Handbook by National Semiconductor. The circuit is...