Apr 20, 2012

2 Tone Ringtone Generator Circuit

The IC LS1240A from SGS Thompson is specifically designed for generating a 2 tone ringtone generator circuit. Thus the IC specifically becomes suitable for landline telephones for producing the ringtones when a call is received.
However with little modifications the IC can be easily utilized for normal applications, in circuits where a double tone alarm may be required.

Basically the IC is a 8-pin DIL chip resembling the IC 555 and has the following specs:

Very low current consumption yet good audible response at the output.

Internal built-in rectifier stage for rectifying an AC input supply, a filter capacitor is also a built-in feature of the IC.

Hardly any external components required for setting up the circuit.

The tone of the output musical audio can be adjusted externally through a resistor.

If the IC os used inside a landline telephone then the supply to the IC is derived from the line voltage via a 1uF capacitor.

The IC is able to drive a piezo electric transducer directly without the need of inductors or amplifiers.

The IC is also capable of driving a small loudspeaker directly for generating the musical output.

However the speaker must be rated at minimum of 50 Ohms.

The following 2 tone ringtone generator circuit shows how to configure the IC LS1240 as a two tone musical signal generator circuit.


Dual Tone Ringtone Generator Circuit


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