Sound Relay Switch | Electronic Project Circuits

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Sound Switch Control with BC182B

Notes:
This sensitive sound operated switch can be used with a dynamic microphone insert as above,
or be used with an electret (ECM) microphone. If an ECM is used then R1 (shown dotted) will
need to be included. A suitable value would be between 2.2k and 10kohms.

The two BC109C transitors form an audio preamp, the gain of which is controlled by the 10k
preset. The output is further amplified by a BC182B transistor. To prevent instability the
preamp is decoupled with a 100u capacitor and 1k resistor. The audio voltage at the collector
of the BC182B is rectified by the two 1N4148 diodes and 4.7u capacitor. This dc voltage will
directly drive the BC212B transistor and operate the relay and LED.

It should be noted that this circuit does not “latch”. The relay and LED operate momentarily
in response to audio peaks.

source:http://www.zen22142.zen.co.uk/Circuits/Switching/soundsw.htm

Be the first to comment - What do you think? Posted by admin - October 2, 2007 at 9:17 pm

Categories: Electronic Control Tags: sound operated switch circuit, sound relay switch, sound switch circuit diagram

Hand Clap Electronic Control

We have all seen the commercial on TV ………. CLAP – ON – CLAP – OFF – THE – CLAPPER ………… well here is a circuit that will perform that same function.

Circuit operation is as follows. A single hand clap will be picked up by the electric mic which is coupled through C1 into the op amp IC1. The output of IC1 triggers the 555 IC timer IC2 which is configured as a monostable multivibrater. The trigger pulse is stretched by IC2 and outputs a pulse to IC3 a D type flip flop. Because of the three state counter arrangement of IC3, two sharp claps are required before IC3 will output a high to Q1 which will turn on K1 relay and any device connected to K1′s switch contacts. Two more claps will clock IC3 again and will turn off Q1 and any device connected to the K1′s contacts. I had my unit connected to my xmas tree lights so that I wouldn’t have to crawl behind the tree to turn the lights on and off. Sensitivity for the circuit is R3 and should be adjusted so that the circuit ignores normal room noise.

From :: http://home.maine.rr.com/randylinscott/dec97.htm