Interesting piece of electronics... - Page 1
Forum section: electronics / general

author: allanw
author_rank: Frequent Contributor
timestamp: May 07, 2010, 05:31:49 am
content: Some others might have seen this around the internet recently as well.The IC's a optocoupler:http://measure.feld.cvut.cz/groups/edu/osv/4N35.pdfI think it's interesting that they used a 1% resistor...

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 07, 2010, 05:51:23 am
content: What are the usage of all this ?

author: allanw
author_rank: Frequent Contributor
timestamp: May 07, 2010, 05:58:52 am
content: It's a way to remotely detonate a bomb when the cell phone is called. This is a great picture because it shows how the bomb was disabled or something before it was called. Or maybe the bomb just didn't work in the first place. Or they had jammed the signal.What I find interesting and scary is that they use precision electronics to do this. Not that I'm interested in making one myself, of course.

author: armandas
author_rank: Frequent Contributor
timestamp: May 07, 2010, 08:02:30 am
content: Quote from: allanw on May 07, 2010, 05:58:52 amWhere do you see precision electronics? I'd say they use whatever they can scavenge from old consumer electronics products..

author: Grapsus
author_rank: Regular Contributor
timestamp: May 07, 2010, 11:00:22 am
content: I agree, who cares about the precision of the resistor you place on the emitter of this optocoupler? Moreover the overall quality of this system seems awfull...

author: Pyr0Beast
author_rank: Contributor
timestamp: May 07, 2010, 12:49:22 pm
content: On the other hand. It is pretty simple to disarm it(They even went by the book with red and black wire)

author: hans
author_rank: Super Contributor
timestamp: May 07, 2010, 12:52:21 pm
content: The schematic probably is fairly simple, a optocoupler and a relais , that's all. Putting a 1% resistor isn't that exciting at all. Considering that 1% resistors aren't that expensive anymore, I wouldn't even consider using 5% resistors anymore. What's so precision about a standard optocoupler and a resistor? I would consider 0,1% resistors precision technology these days.The built quality is very amateurish though. If they wanted this thing not to be noticeable, then they would at least make it a lot smaller and put it somewhere in the phone.

author: VladKEasternTiger
author_rank: Regular Contributor
timestamp: May 07, 2010, 01:47:30 pm
content: Quote from: allanw on May 07, 2010, 05:58:52 am

author: VladKEasternTiger
author_rank: Regular Contributor
timestamp: May 07, 2010, 02:03:40 pm
content: Can someone please explain to me in Laymans terms how this works? Why did they use an old Nokia?

author: Unknown
author_rank: Unknown
timestamp: May 07, 2010, 02:37:30 pm
content: Quote from: shafri on May 07, 2010, 02:07:58 pmI'm sure the iphone has an app for that!

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 07, 2010, 02:47:07 pm
content: I have build lots of this bombs , so to detonate the power on switch of large RF transmitters ,that are set on nearby mountains, around the city ( UHF & FM ) ..Those transmitters some times they close down from a Mains Interruption ( Power failure) ,or "false" high SWR indication .So some one needs to just reboot them manually.Those transmitters power up in sequence their RF stages with some delay of few seconds per stage.In order to do that, we use the cell phone , one dark box with a photo resistor ,and one small PCB .So when you ring that number ... the phone rings the display of it gets illuminated ,the photo resistor reacts, and triggers the circuitry ..There is nothing magic to it , but the word "Bomb" it does trigger the imagination

author: RayJones
author_rank: Frequent Contributor
timestamp: May 07, 2010, 08:52:46 pm
content: So, does the blue switch invoke "Martyr Mode"?1% resistor?They fall out of the trees these days, a single 1% resistor hardly makes a precision instrument.

author: VladKEasternTiger
author_rank: Regular Contributor
timestamp: May 07, 2010, 08:54:46 pm
content: Quote from: Kiriakos-GR on May 07, 2010, 02:47:07 pmYou explained it well it reminds me off the ROOMBA cleaner, when it bumps into something the bumper inside blocks part of the laser beam therefore the motor stops in that particular direction and the resistance is changed. The think I dont understand is how does the circuit when the photoresistor make the mechnical device to activate, sure the resistance changes when the photocell is activated by the phones lcd display but the next thing I dont get is when the circuitry is triggered how does this make the mechnical side of things kick in? Unless a relay is being used?

author: RayJones
author_rank: Frequent Contributor
timestamp: May 07, 2010, 09:13:59 pm
content: Quote from: VladKEasternTiger on May 07, 2010, 08:54:46 pmThe original photo does not suggest a optosensor is being used to watch the backlight.It does however use an optocoupler, an entirely different beast.Most likely the LED half is "bolted" onto the ringer inside the phone.The optocoupled transistor provides extra oomph to drive the relay coil, and the contacts of the relay connect to the whammmo bundle.So ring the phone, LED lights, transistor turns on, relay turns on, bang goes off.A telemarketer could set this little beauty off inadvertantly.Perhaps the little blue switch is a "safety" push on, push off that the opens the power to the relay to avoid premature ejaculation on the way to martyrdom.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 07, 2010, 09:53:22 pm
content: Quote from: RayJones on May 07, 2010, 09:13:59 pmYes , what I had posted its how we do it in Greece..Its simple, low cost , and practical ..And it called as remote activation by cell phone .. you can use it , to start the air condition , so to heat your room , before you get home .. or for another hundreds of reasons..The young ones call it as Bomb activator , well there is hundreds of ways to do that too.But personally I do not get excited with the name " Bomb activator " ,for the expert ones in electronics , those are common projects and nothing more .Ones I was had a contract to service the alarm system of one chain of super markets,they was as 5-6 in my area .They had also Cell phones to act in the reverse way , and do the emergency call .So now I can say that I had do them all ... remote activation by cell phone , and the opposite .

author: VladKEasternTiger
author_rank: Regular Contributor
timestamp: May 10, 2010, 07:44:15 am
content: Quote from: Kiriakos-GR on May 07, 2010, 09:53:22 pmIf you know any youtube videos or pictures of what you just said especially about your heater device please share with me, Im so very interested in this.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 10, 2010, 03:28:26 pm
content: Sorry , no videos , no Youtube ..The PCB that does the job , are Greek design , Greek manufacturing.And its marketed by an medium sized company in Athens.An customer of my got it , and I did the dark box from aluminum, and added foam inside,and I had add also an permanent small phone charger.The circuitry gives an output of 12V , good enough to drive one normal size 220V panel relay .