Sound Activated Camera Flash

Introduction: Sound Activated Camera Flash

About: Working my dream job in the Telecom industry, so chances are, i'll never have time to respond to comments or messages, nothing personal.

A quick and dirty and dangerous sound activated flash to catch moments in time

Step 1: The First Thing You'll Need Is an Amplified Computer Speaker

The sacrificial victim here is a pair of harmon kardons from a garage sale $1

Step 2: Crack the Case Open and Identify the Op Amp Used

then go to mouser and download the datasheet, in this case the chip is a ba4560. your looking for which pins are the amps +&- ins, there should be two pair. To determine which pair you need touch the leads (with power on) of a speaker to each pair of pins, one pair should give a much louder feedback than the other. Note those two pins.

Step 3: In This Step We'll

disconnect the leads from the speaker, cut the traces to the RCA jack that the slave speaker connected to, and attach hookup wires to the op amp pins we identified.

Step 4: Next Take the Hook Up Wires You Connected to the Op Amp and Attach Them to the Speaker.

They are attached in series with a 1 k pot and a 3.6 micro farad capacitor, the pot acts as a sensitivity control.

Step 5: Now You'll Need an SCR

I used a 2n687, I tried a couple of diff ones before I found one that works, I hope you have a good junk store near by, mine came from Skycraft in Orlando. Anyways to hook up the SCR attach the the positive lead that originally went to the speaker to the SCR's gate. The negative lead to the speaker is attached to the SCR's Cathode. At this point a multimeter in diode mode across the SCR can be used to verify operation. So power up and test you'll get a variable reading across the SCR when you tap the speaker if it's working

Step 6: Connect the SCR to the RCA Connector

This is easy, just jumper the anode and cathode of the SCR to the RCA connector

Step 7: Now to the Camera

Cut the cord off the slave speaker and set it aside, get a disposable camera from a drug store or someplace. BTW CVS hooked me up, Walgreens gave me the Bum's Rush. Crack open the camera, remove the battery and short the big capacitor, getting zapped hurts, so be careful. examine the mechanism to identify the flash trigger switch and attach the end of the cable you set aside to either side of the switch.

Step 8: At This Point Your Almost Done.

seal up the camera (put the battery back in), plug the cord from the camera into the modified amp, hook up power and tap the speaker, if it doesn't flash reverse the leads and try again, if it still doesn't work, I dunno? it worked for me. One thing about the power, use a battery, I used a nine volt, the 60hz hum from the transformer messed it up.

here's some pix These were taken with a Canonette film camera with ISO 400 film, you need absolute darkness, so set up, flip the lights off, open up the shutter, drop something, close shutter and turn the lights back on to reset. Sorry about the pictures I realise this is not the clearest of instructables, but i think with some though you can follow it. Remember EMP kills.



    • Creative Misuse Contest

      Creative Misuse Contest
    • Tiny Home Contest

      Tiny Home Contest
    • Water Contest

      Water Contest

    20 Discussions

    That makes for really cool photos, have you seen the smash bat, it works on the same type of thing only instead of sound it uses a touch sensor in a bat so they can capture pictures as they bust the crap out of melons and other fun things

    So, let me get this straight. You cut off the sound input and speaker wires from the op-amp, switch them around so the op-amp is amplifying the signal it gets from the speaker (acting as a microphone), and you wire up the amplified output of the op-amp to the SCR to switch the flash? That sounds totally doable- could you just use a microphone and an op-amp or are you using other bits of the computer speakers as well?

    1 reply

    That sounds about right (remember it's been two year), and yes you could probably rig a opamp the same way, I just had these handy.

    Ok im really sry i cant figure this out. Im only 15 but i want to learn how to do this stuff. Here are some pictures i took of the altec lansing speaker i tore apart. could you tell me where to put some of the connections. Im not really sure what to do.

    Speaker guts 001.jpgSpeaker guts 002.jpgSpeaker guts 003.jpg
    1 reply

    That's alright, gimme a couple days, I have the flu right now and I haven't looked at this project in two years ;-) My brain is running slow... Do you have a multimeter? If not and you have a harbor freight nearby they are only $3.

    sry im a noob at this and i dont know how to find the chip number to download the data sheet. plz help thanks

    1 reply

    We all were once ;-) On top of the circuit board the chip is black rectangle with 6 or 8 legs, the number is printed on the chip, you might need a magnifying glass to read it. If there is no number, it means it's a cheap chinese rip off.

    so how many times did you accidentally set it off?

    lol is that a failed egg i see? great work buddie i just finished mine works flawlessly mus put up some pics and i express my utmost condolences for your digi camera TIMm

    1 reply

    One of MANY failed eggs. I'd like to see some of your pix when you have the chance

    evry thing electric makes electric emp its just not strong i dono why this makes a strong emp cause nomally it takes a nuke or a power transformer to have strong enogh emp to mess up any thing


    11 years ago

    This is great. I'm definetly going to have to do this. I'm glad you took it to a new level.


    11 years ago

    Love the picture of the egg - good work

    glad to see you got this working... sorry to hear it killed your digicam :/