Sound operated switch

saraf_nikhil · Post by **saraf_nikhil** » Tue Jan 24, 2006 9:01 am

Im supposed to make a sound sensitive device that'll respond to basic sounds like a clap and give either a sound output or an LED light-up or both. One of the project guides that I bought, however, used a device called THYRISTOR which is not available anywhere here. Its basically some conducting gate for allowing current to pass. Can I use any other device or make the project using some other simpler, easily available items? Please Help....

THANKS,

Nikhil

deleted-71254 · Post by **deleted-71254** » Wed Jan 25, 2006 1:14 pm

Nikhil,

A thyristor would allow AC current to be switched... that is... that it would control household appliances. However, if all that you are doing is turning on an LED, I would suggest replacing the thyristor with a "Darlington Pair". This is a pair of transistors with the emitter of the first transitor tied to the base of the second and the collectors of both transitors tied together... it affords very high gain (amplification) to turn on a DC current in the collectors. An LED with an appropriate current limiting resistor may be placed in series with the collectors.

Here is an explaination of a darlington pair and it's usage:

http://www.technologystudent.com/elec1/transis2.htm

Good luck!