Telephone line monitor (CB10149E)

We found this circuit in a 1980s publication on telephony. The circuit uses an integrated amplifier from that time, which is uncommon today.

| Clique na imagem para ampliar |

Direct Reading Capacítancemeter (CB3885E)
We find this circuit in American documentation from the 1980s. The accuracy of the circuit depends on the...
Non-Inverter Amplifier LM139 (CB14247E)
The presented circuit uses a symmetrical power source to supply an amplifier with the LM139 or...
5 W Audio Amplifier (CB467)
High quality sound can be obtained from this transistor amplifier. The output transistors must be...