Laser Espionage Microphone (how-to)

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Lasers Listener Experiments Spies How Homemade Science Espionage Microphone Hacks Cool Free Tutorials DIY
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  • Updated: 19-Mar-08
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  • Added: 15-Aug-07

Listen inside of a building hundreds of yards away using a laser.Please rate, comment, and digg!!

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Comments on

Laser Espionage Microphone (how-to)

48 Comments | Add Comment
  • Nice project

    Good explanation and instructions. 5 stars!

    By HouseholdTech 1187206992 Reply Spam [+19] Moderate Up Moderate Down
  • Nice!...

    I saw this was mentioned on the tv show "Burn Notice" as a listening device used by fbi, etc... He took a picture from his window with a digital camera to see if there is a laser microphone, saw the dot it produced in the camera... and then they strapped a vibrator to the window to prevent them from listening. Good show... And Good DIY Video!! 5*'s

    By cRiTiCiZeD 1187244663 Reply Spam [+3] Moderate Up Moderate Down
  • sound

    sound from light ? strange

    By colzyUK 1187202877 Reply Spam [+1] Moderate Up Moderate Down
    • Why is it strange?

      Telephone signals travel over fiber optic cables all the time. So do television signals. It's called modulation.

      By FrankDK 1187218568 Reply Spam [+1] Moderate Up Moderate Down
    • I might be wrong, but...

      ... The light in an optical wire is turned on and off to create bits just like the computer does.
      Doesn't this photocell measure the wavelenght of the light that hits it and translate it into diffirent voltages which then is translated to sound through a speaker?

      The wavelenght of the laserlight will change everytime the window vibrates cause it has a longer or shorter distance to travel to hit the window.

      I realize that FrankDK just illustrates that the transition from light to sound is not so farfetched, but it is done in two diffirent ways in this video and in a optical wires.

      By KaiSan 1187251523 Reply Spam Moderate Up Moderate Down
    • Sort of

      It's the amplitude of the beam that's being measured by the cell - the wavelength is a constant (in the case of a red laser pointer, 650nm) :)

      By Funditor 1187264057 Reply Spam Moderate Up Moderate Down
  • problem?

    how easy is it to reflect a tiny laser dot off of a window onto an equally as small photocell hundreds of yards away? seems pretty tricky

    By josniffigous Rex 1244853770 Reply Spam Moderate Up Moderate Down
  • Why is it so difficult to understand?

    You don't need a laser with a reflector, you're reflecting the laser pointer off the glass window then back into the photocell. The vibrations in the window from speech or other sounds will cause the laser to fluctuate on the photocell which translates into sound. It's not good quality sound, but it's enough to hear what people are saying. This is extremely simple and you're all making it really complicated. $2 laser pointer, go to a pet store and buy one of those cat ones. $.50 photocell from radioshack. $1 headphone cable. That's it. Mount the laser so it can't move and secure it on somehow. Mount the photocell so that the reflection of the laser off the glass window will hit it straight on. Plug the other end of the headphone cable into the mic port on your computer and hit record. Any sounds inside the room will result in the light's amplitude changing, which translates into sound from the photocell.

    Simple.

    By HaLo2FrEeEk 1243806047 Reply Spam Moderate Up Moderate Down
  • help?

    i cant find any headphones that have 3 wires, i checked all kinds of 3.5 mm audio jacks, headphones with and without mic, and a couple dollar store models of headphones. no luck. any suggestions?

    By nyupfront 1230963787 Reply Spam Moderate Up Moderate Down
  • Helping a novice

    First, this is a great video thank you. I'm trying to understand this, forgive the newbie over here.

    The laser reflects off a window, and the vibrations are translated into sound then into the computer.

    How does the reflection get sent to the diode however? I see some comments mentioning lazer pointers with led ends that are reflectors, however I'm unable to find anyone online.

    Thanks for the help, assuming someone replies!

    By enigma66 1230530294 Reply Spam Moderate Up Moderate Down
  • good idea........

    but your explanation is lacking. you need to go into more detail on the set up and such. the average person is not going to understand what you mean or are doing.

    By lowellfranck72 1226941650 Reply Spam Moderate Up Moderate Down
  • Interesting

    Cool vid...maybe you should check out this video comp i found on youtube. The video ID is: BI7gn6eYgW8

    By loutoon 1218447216 Reply Spam Moderate Up Moderate Down
  • Question?

    What laser is this? Where I get it?please tell me

    By kalev 1196104827 Reply Spam Moderate Up Moderate Down
  • Reflector?

    I google'd "Laser Pointer with Reflector" and came up with nothing? Did you make the little thing coming out of the back of the laser that shoots it back at the photo cell?

    By object_being 1196035478 Reply Spam Moderate Up Moderate Down
  • OK BUT

    Who need this ??? Even if someone give it to me I wouldn't use it

    By TAMARIN 1192981930 Reply Spam Moderate Up Moderate Down
  • nice

    good steps,

    By Cammy911 1192940025 Reply Spam Moderate Up Moderate Down
  • refferences on the pointer

    Hi,
    I would like to have the refrences of the pointer you used in order to buy the same. is any laser pointer sold with a reflecter?

    By kiki0077 1191621785 Reply Spam Moderate Up Moderate Down
  • WHT is it

    whts the little bit that is coming out of the laser pointer?!?!?

    By silentDMX 1190572619 Reply Spam Moderate Up Moderate Down
  • Maybe im stupid but

    i cant find a laser pointer like that that has a relecting thing at the back... certainly not a 2 dollar item.

    By FatPumPumLovah 1188421140 Reply Spam Moderate Up Moderate Down
    • there is no reflector people

      its a cheap laser pointer i've seen in many films on metacafe. i happen to have gotten mine at cvs. they are like 3 bucks and the extra little arm thingy has an led in the end of it. thats why there are 2 buttons on the side!

      By Twi7ch 1200360319 Reply Spam Moderate Up Moderate Down
  • Distance Issue

    Although you could use this with pretty good results for relatively small distances, even better with an AF amplifier after the photo cell, it gets pretty useless for larger distances because lasers avaiable to public still have a considerable beam angle, and the beam becomes larger and weaker as the distance gets bigger. Nevertheless, a good idea to use if you need it and you know how to solder a couple of wires :P

    By sinekt 1188084336 Reply Spam Moderate Up Moderate Down
  • what ?

    your laser mic is good if you can get the laser to reflect back onto the photocell . listening to a conversation in a building even 50 metres away would require you to be directly in line with the window . looks good in hollywood , but impractical in real life !! well done tho !!

    By dragon_64 1188002092 Reply Spam Moderate Up Moderate Down
  • Cool!

    Very cool idea! I recommend taht you use a some kind of Infra Red laser pointer, otherwise people behind that window could see you. But there is another prob: how do you know when the light is hitting the photocell? Easy! Just turn on a digital camera and help yourself with it! Why? Because cameras ca actually see what a human eye cant: infrared :)

    By David1994 1187968301 Reply Spam Moderate Up Moderate Down
  • !

    Video of the month! Great stuff man! Keep it up! Five stars!

    By RunFreeTV 1187360424 Reply Spam Moderate Up Moderate Down
  • I like it!

    But I'm curious as to the max. effective range? And if I used an IR laser, how would I be able to see if it was focuse on the photo-cell?

    Props on the idea though, I've seen it before on a show about why the CIA and FBI now have dual paned seperated windows outside their buildings.

    :)

    By Lance Corporal â„¢ 1187243516 Reply Spam Moderate Up Moderate Down
    • Well

      The effective range I don't know. Fairly limited with a cheap laser, but quite good with an expensive one and a lens to focus the beam.

      For using the IR laser, you can use nightvision equipment or an IR equipped camera.

      By Funditor 1187264175 Reply Spam [-1] Moderate Up Moderate Down
  • And then.......

    they see the red dot shining on their inside wall (lasers go through glass as well as reflect). They will call the police on you and you will get busted.

    By pennsteve676767 1187224239 Reply Spam Moderate Up Moderate Down
    • Near-IR

      Use an infrared laser with, say, roughly 800nm light.

      The light is invisible to the eye, but you can still see the reflected spot using a digital camera (which can see near-IR light.)

      By karmabandit 1187229150 Reply Spam [+1] Moderate Up Moderate Down
  • i knew this

    before and i was sure that federals would use that, but to see this could be done so easy and cheap by everyone scares me quite a bit!

    By 4k33m 1187222903 Reply Spam Moderate Up Moderate Down
  • Incredible...

    Nice video...But i'm happy to live very far from you... ;-D
    5`````and digg.

    By LUCCHINA 1187220825 Reply Spam Moderate Up Moderate Down
  • confused

    how do you get the laser to reflect back to the photocell?

    By lukewarm27 1187210037 Reply Spam Moderate Up Moderate Down
  • So you actually have to go into the room

    Can you do this without preparing the room. ie for spying on next door?!

    By pieisgood 1200128540 Reply Spam [-1] Moderate Up Moderate Down
  • This is BS

    You can't create an audio signal using a resistor. The photocell RESISTS current, it does not create it! This is possible, but requires a much more complex circuit.

    By Ziggythewiz 1198277609 Reply Spam [-1] Moderate Up Moderate Down
  • Find hot ringtones

    Get ringtones at RINGTONESET dot NET

    By retashowsdollgc 1189567431 Reply Spam [-1] Moderate Up Moderate Down
  • eee yea...

    GOOD LUCK trying to allign the laser reflection onto the LDR (Light Dependant Resiter - ''photocell'' my arse!)!!! also, i doubt this works on double glazed or even triple glazed windows ;)!!

    By mttw 1188320279 Reply Spam [-1] Moderate Up Moderate Down
  • question

    what is the black wire protruding from the back of the laser pointer and what is an easier way to see if the laser pointer is hitting the sulfide photocell

    By kamakazi103 1188163350 Reply Spam [-1] Moderate Up Moderate Down
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