Sun-Up Alarm


Posted on Dec 7, 2012

The Sun-Up Alarm can be used to provide a audible alarm for when the sun comes up or it can be used in a dark area and detect when a light comes on. It can also be used to detect a light beam, headlights etc. The circuit works as follows. The phototransistor is very sensitive to light. (Any phototransistor will work fine) The sun shining on this device will provide a high to one of the NAND gates. This will cause another NAND gate to oscillate which will drive another gate to output a 100hz tone. The transistor provides drive for the speaker.


Sun-Up Alarm
Click here to download the full size of the above Circuit.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

30V from 5V converter
Am demodulator
Gated pulse descrambler
Differential analog switch
basic cds photocell detector
Automatic Mains Disconnect
How To Build A Sequential Timer Using A Cmos 4017



Top