Door buzzer sound with CD4001 CD4060

Saturday, June 18th, 2011

The Door buzzer sound circuit was two-tone sound. With the switch S1. working of circuit,The IC1 is a frequency dividing circuit, and generator a sound frequency came out.by the C1, R1 are the frequency generator. This audio signal from pin 7 and pin 4 into the pin 1 and pin 8 of the IC2a, IC2c [...]

Doorbell for the Deaf

Tuesday, June 7th, 2011

This circuit provides a delayed visual indication when a door bell switch is pressed. In addition, a DPDT switch can be moved from within the house which will light a lamp in the door bell switch. The lamp can illuminate the words “Please Wait” for anyone with walking difficulties. The circuit uses standard 2 wire [...]

ultrasonic dog whistle circuit

Wednesday, May 25th, 2011

It’s well known that many animals are particularly sensitive to high-frequency sounds that humans can’t hear. Many commercial pest repellers based on this principle are available, most of them operating in the range of 30 to 50 kHz. My aim was, however, to design a slightly different and somewhat more powerful audio frequency/ultrasonic sound generator [...]