Instructables
A quick and dirty and dangerous sound activated flash to catch moments in time
 
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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.
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
junits155 years ago
that is really clever, nice job
PKM5 years ago
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?
Tool Using Animal (author)  PKM5 years ago
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
Tool Using Animal (author)  soundman31036 years ago
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.
Hey i got another question are we supposed to cut the wires comming from the black think. Here is the data sheet for it http://www.datasheetcatalog.com/datasheets_pdf/T/D/A/7/TDA7350A.shtml
thanks so much for all of your help
Tool Using Animal (author)  soundman31036 years ago
No, don't cut the leads, just add the jumper wire.
sry im a noob at this and i dont know how to find the chip number to download the data sheet. plz help thanks
Tool Using Animal (author)  soundman31036 years ago
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.
schimmi6 years ago
so how many times did you accidentally set it off?
Ian017 years ago
Why does this produce an EMP?
Kataze Ian016 years ago
I think that was more of a public service announcement than anything else.
Might I suggest http://www.datasheetcatalog.com/ There are lots of datasheets there which mouser might not have.
som3thing7 years ago
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
Tool Using Animal (author)  som3thing7 years ago
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
phinch8 years ago
This is great. I'm definetly going to have to do this. I'm glad you took it to a new level.
Spanky8 years ago
Love the picture of the egg - good work
trebuchet038 years ago
glad to see you got this working... sorry to hear it killed your digicam :/