Description
This is a simple home telephone ringtone generator circuit which is
built with applying only several electronic components / parts. It
generates simulated telephone ringtone and requires only DC supply with
4.5V DC to 12V DC voltage.
One may possibly use this circuit in ordinary intercom or phone-type intercom. The sound is pretty loud when this circuit is operated on +12V DC power supply. Even so, the volume of ring sound can be adjusted.
One may possibly use this circuit in ordinary intercom or phone-type intercom. The sound is pretty loud when this circuit is operated on +12V DC power supply. Even so, the volume of ring sound can be adjusted.
Circuit Diagram
CD4060B is chosen to produce three kinds of pulses. Preset VR1 is
fine-tuned to get 0.3125Hz pulses at pin 3 of IC1. At the same time,
pulses obtainable from pin 1 will be of 1.25 Hz and 20 Hz at pin 14. The
three output pins of IC1 are connected to base terminals of transistors
T1, T2, and T3 through resistors R1, R2, and R3, respectively.
Working with a built-in oscillator-type piezobuzzer generates about
1kHz tone. In this particular circuit, the piezo-buzzer is turned ‘on’
and ‘off’ at 20 Hz for ring tone sound by transistor T3. 20Hz pulses are
obtainable at the collector of transistor T3 for 0.4-second duration.
Just after a time interval of 0.4 second, 20Hz pulses become again
obtainable for another 0.4-second duration. This is followed by two
seconds of nosound interval. Thereafter the pulse pattern repeats by
itself.
Author K.UDHAYA KUMARAN, VU3GTH
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