Telephone Ring Generator Using Small Power Transformer
Telephone circuits

Telephone Ring Generator Using Small Power Transformer

By Bill Bowden


This ring generator will ring a telephone once every 10 seconds.

The interval between rings can be lengthened or shortened by varying the value of the 1 Meg resistor. The 70 volt/ 30 Hz ring voltage is produced from the 120 volt side of a small 12.6 VAC power transformer (Radio Shack 273-1365). Both capacitors connected across the transformer windings are non-polarized / 100 volts. Circuit draws about 300mA from the 12 volt DC power supply during the ringing interval.

Telephone Ring Generator Using Small Power Transformer circui
Telephone Ring Generator Using Small Power Transformer circuit

2730 22 August 2007

See also:

2 line intercom plus a telephone changeover switch
The circuit presented here can be used for connecting two telephones in parallel and also as a 2-line intercom.
Telephone Ring Generator Using Switching Supply
The telephone ring generator shown below generates the needed high voltage from a simple switching mode power supply.
Telephone Audio Interface
Audio from a telephone line can be obtained using a transformer and capacitor to isolate the line from external equipment.

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