Electronic phone bell


Posted on Sep 15, 2012

The speaker emits a distinctive warble tone when ring pulses are applied to the phone line. Use this circuit as a remote bell or disconnect the phone`s ringer for direct use. Rl adjusts the duration of the output; R2 and R3 control the tone`s duty cycle and frequency. The transistor is a general-purpose NPN photodevice


Electronic phone bell
Click here to download the full size of the above Circuit.

The neon bulb and transistor are coupled with the heat-shrink tubing to form an optoisolator.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

FM Broadcast Audio Transmitter
Phone line audio muting circuit
Read-head-preamplifier
arduino + optotriac based ac dimmer blinking severely
mobile incoming call indicator
3 band equalizer circuit
Voice modulator circuit
Mechanical TV System
Parallel port programming
Comments on the Circuits of the first Transistor Radios
LM741 OpAmp Voltage Indicator
An attenuated tone control circuit diagram
PQS1 series magnetic disk control panning control circuit



Top