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

50 Watt power Amplifier
Battery Current Sensor
Half-wave rectifier
PT7M6101 Ultra Low Voltage Detectors
XC6121 Voltage Detector With Watchdog Function And ON/OFF Control
Remote Control Your Computer
One Of Nine Sequencer
Simple Characterization Circuit for Rechargeable AA Cells
Portable alcohol detector alarm circuit
KD9562 octave analog sound music circuit
IN8510 and power motor driver circuit composed of DAC7520



Top