Telephone Record Control by 2N4360 FET, 2N2222 and 2N2102

You can connect your phone to any recorder device which has a mic and remote control input. This circuit automates the recording process when the phone is in use.

After constructing the circuit, first measure the telephone line voltage with a multimeter and connect the positive and negative terminals of the circuit to the line as shown in the diagram. Repeat the same step for the remote input and connect the circuit to the remote input.

The circuit does not require any external power supply since it gets its power from the phone line.

Circuit operation is so easy. When the phone is on hook, the 2N4360 FET is in cut off mode since the line voltage is about 48VDC. When the phone is picked up, the line voltage drops to 10VDC , then FET turns on along with 2N2222 (Q2) and 2N2102 (Q3) and finally the device starts recording. The device must be in record mode at all times.