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Sound Operated / Sound Activated Circuits
#'s - R     S - Z


Last Updated: November 22, 2021 03:00 PM

Circuits Designed by Dave Johnson, P.E. :
Sound Triggered Night Light -  A while back, I received a schematic from a guy by the name of Karl.  He described a situation he and his wife found themselves in aboard a cruise ship in the Caribbean.  They were staying in a room toward the inside of the ship, which did not have any port holes, windows or a balcony. . . Circuit by David A. Johnson P.E.-August, 2013

Switch Detects Audio Signal -  This circuit will activate a transistor switch when it detects at least 50mv peak to peak of an audio signal.    it could be used to turn on a relay, routing the signal to were it is needed.. . . Circuit by David Johnson P.E.-July, 200

Transistor-Switch Detects Audio Signal -  For some audio systems it is desirable to have an automatic switch circuit turn on other devices, such as an amplifier, if an audio signal is detected on one line.  The hobby circuit below will activate a transistor switch when it detects at least 50mv peak to peak of an audio signal.  The switch could be used to turn on a relay, routing the signal to where it is needed.  A single 3v lithium cell will power the electronic circuit for about 5 years . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

Capacitance Proximity Switch
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Links to electronic circuits, electronic schematics and designs for engineers, hobbyists, students & inventors:

Scanmate - Audio Activated Recorder -  ScanMate connects between your scanner and tape recorders (via the recorder's microphone or auxiliary input and its remote start jack). __ Designed by Tony van Roon  VA3AVR

Seismic Sensor -  My original "Deer Repellent/ Seismic Sensor" recommended using a speaker with a weight glued to the cone as a vibration sensor (see bottom of page) but it recently occurred to me that the speaker could supply the mass itself.  By gluing  __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Set Your Lights to Music -  6-Aug-09 EDN-Design ideasThis circuit activates six ac outlets according in a logarithmic thermometer-code format, causing six to 12 strings of lights to flash on and off according to the level and tempo of music you are playing Design by Hanif Saeed, Maxim Integrated Products, Inc, Sunnyvale, CA

Sound Activated Relay #1 -  This relay remains dormant until the op-amp activates upon sound via the electret-microphone.  I only tested the 2-wire type.  The input stage is a regular off-the-shelf 741 operational amplifier and connected as a non-inverting follower audio amplifier.   __ Designed by Tony van Roon  VA3AVR

Sound Activated Relay #2 -  This relay remains dormant until the op-amp activates upon sound via the electret-microphone.  Only tested with the 2-wire type.  The input stage is a regular off-the-shelf 741 operational amplifier and connected as a non-inverting follower audio amplifier __ Designed by Tony van Roon  VA3AVR

Sound Activated Switch -  This project is a sound activated switch.  Description Clap switch/Sound-activated switch designed around op-amp, flip-flop and popular 555 IC .  Switch avoids false triggering by using 2-clap sound.  Clapping sound is received by a microphone, the microphone changes the sound wave to electrical wave which is further amplified by op-amp.555 timer IC acts as mono-stable__ 

Sound Controlled Flip Flop -  Described here is a very inexpensive solution to many phono-controlled applications like remote switching on, for instance, or activating a camera, tape recorder, burglar alarms, toys, etc.  The circuit given here employs a condenser microphone as the pick-up.  A two-stage amplifier built around a quad op-amp IC LM324 offers a good gain to enable sound pick-up upto four metres.  __ 

Sound Operated Switch -  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. __ Contact IQ Technologies

Sound Operated Switch -  This sensitive sound operated switch can be used with a dynamic microphone insert as above, or be used with an electret (ECM) m`icrophone.  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 __ Designed by Andy Collison

Sound Triggered Night Light -  A while back, I received a schematic from a guy by the name of Karl.  He described a situation he and his wife found themselves in aboard a cruise ship in the Caribbean.  They were staying in a room toward the inside of the ship, which did not have any port holes, windows or a balcony. . . Circuit by David A. Johnson P.E.-August, 2013

Sound-Operated Intruder Alarm -  When this burglar alarm detects any sound, such as that created by opening of a door or inserting a key into the lock, it starts flashing a light as well as...__ Electronics Projects for You

Sound-Operated Switch for Lamps -  This inexpensive, fully transistorised switch is very sensitive to sound signals and turns on a lamp when you clap within 1.5 metres of the switch.  One of its interesting applications is...__ Electronics Projects for You

Switch Detects Audio Signal -  This circuit will activate a transistor switch when it detects at least 50mv peak to peak of an audio signal.    it could be used to turn on a relay, routing the signal to were it is needed.. . . Circuit by David Johnson P.E.-July, 2006

Transistor-Switch Detects Audio Signal -  For some audio systems it is desirable to have an automatic switch circuit turn on other devices, such as an amplifier, if an audio signal is detected on one line.  The hobby circuit below will activate a transistor switch when it detects at least 50mv peak to peak of an audio signal.  The switch could be used to turn on a relay, routing the signal to where it is needed.  A single 3v lithium cell will power the electronic circuit for about 5 years . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

Ultra-Sensitive Solid State Clap Switch -  Here is the circuit of a highly sensitive clap switch that can be operated from a distance of up to 10 metres from the microphone.  Signals picked up by the microphone are amplified by transistors T1, T2, and T3.  Diode D1 detects clap signals and the resulting positive voltage is applied to the base of__ 

Ultrasonic Dog Whistle -  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.   __ Designed by Tomaz Lazar-Ljubljana, Slovenia

Voice activated switch  -  This circuit uses an MC2830 to form a voice activated switch (VOX).  A traditional VOX circuit is unable to distinguish between voice and noise in the incoming signal.  in a noisy environment, the switch is often triggered by noise, or the activation sensitivity must be turned down.  This circuit overcomes this weakness.  The switch is activated by voice level above the noise and not activated by background noise. __ Contact IQ Technologies

Voice identifier for a repeater station -  Designed as a drop-in replacement for the VHF Engineering repeater's CWiD, it can be used in other equipment too. __ Designed by Manfred Mornhinweg

Voice Operated Switch -  Description This circuit is a voice operated switch (VOX) and designed for audio frequencies within a commercial telephone bandwidth of 100Hz to 3000Hz.  input amplitude is sensitive down to 10mV and the output comparator can drive a relay or interface to micro processors and TTL switching between 0 and 5Vdc.  Notes The VOX circuit is […]__ 

Voice Recorder & Playback System -  There are several types of voice recorder and playback systems available in the market but most of them are expensive and their circuits are also very complex to assemble.  Here is...__ Electronics Projects for You

Wave Multiplier for music Synthesizers -  The idea for this project came from the fabled middle section of the Serge wave multipliers.  At the time I designed this, I had never seen or heard one of these units, nor had I seen its schematic diagrams, but armed with descriptions and suppositions by various people who had seen them, and a couple of photos of CRO traces from the output of the module, I decided to design myself one. __ Designed by Ken Stone

Whistle Activated Switch Using Um3763 -  Surprisingly much, can turn on – shut down electric devices with a whistle sound.  This is simple sound control circuits, that different from a little common circuit is Requires high frequency noise Such as whistle sound etc.  The heart of working in this circuit is IC 1 (UM3763) that is designed for this particular work.  Figure__ 

Whistle On-Whistle Off -  This CMOS toggle flip flop circuit has an addition of2bandpass filters and condenser microphone so the relay can be toggled by whistling at it.   __ Designed by Bill Bowden

Whistle Responder -  Beeps when hears your whistle; A gadget suitable for key-holders, games etc __ Contact Flavio Dellepiane, fladello @ tin.it

Whistler: Electronic Trainer/Coach -  This device makes it possible to generate beeps at chosen regular time intervals for timing track race training.  Each time interval is indicated by a beep, and the end of a performance test is indicated by a double beep.  Two types of test are allowedmust register on this site __ Designed by Published in Elecktor July/Aug, 2010

Got Designs?
Please eMail
if you want me to link to and/or post your original design Thanks.


Sound Operated / Sound Activated Circuits#'s - R     S - Z


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