Picture of Make a remote controlled camera from a cellphone!
Want to know what your cat is doing while at work? Send a text message to your newly made surveillance-cellphone and receive pictures and videos seconds later. Sounds like a dream? Not any more!

This video explains how it works:

Step 1: Parts and tools you need

Picture of Parts and tools you need
A brave camera-cellphone (including SIM-card). I'm currently using a Sony Ericsson T630.
A microcontroller (I use a Picaxe 18x)
Solenoid relays
Photoresistor (LDR)
A few resistors might come in handy
Soldering iron
Solder, cutters, tape etc.

Oh, and another working cellphone.
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asharma1311 year ago


tsmitt13 years ago
Could you send me schematics at tom.smitt1337@gmail.com I would much appreciate this. Thanks in advance.
shifranmjm3 years ago
realy nice very good,
rush_elixir6 years ago
you got 5 star from me very good work. please add elaborate pictures, schematics and more intructions. better yet a detailed video on how to construct one step by step. thanks
hi this sasi
you got the schmatic diagram for that,if you can send me pls this id,sasikumar1357@gmail.com
very nice kindly send me schmetic diagram ,than only i will try,nice consept, and how to program the programmble ic,and part list and all pls send me my e mail id .sasikumar1357@yahoo.co.in or sasikumar1357@gmail.com
i am exporting your reply i need to make project this nice consept
srikanth3333 years ago
can i use microcontroller 8051 in place of picaxe?
longjasp3 years ago
nice prject!! can i have the full schematic diagram? pls send me it here princessmalou.longjas@bohol.asia..... thnx n advance
ilpug4 years ago
looks like a bomb though, but nice build.
pjain7 ilpug4 years ago
yup... at first it does look like a remote controlled bomb..

great one man.. keep this goin on and on and on...
So you technically have to pay for 2 phone bills? Because im pretty sure texting has to have a service to like connect to and stuff...just curious ;D
ciochinda4 years ago
Hy guys! I'm from Romania (Europe)
- i'm new here (in fact i just signed up, because i had an similar ideea and i just had to tell it to somebody)
- I have got no electronic knowlege, but I had another ideea for this rig (and I say it's much smaler and kuicker to build)
- but i got to say i never tried to build it (is just an ideea)
- its probably more expensive (the phones i mean) but they both are perfectly usable (you don't mess with them in almost any way)

what you need:
- 2 phones (both newer models with 3G network (with video call available) - one electric motor
- one light sensor (posible from a solar garden lamp)
- a carboard box (around the phone and everithing ealse - exept for a little hole for the camera, ofcorse)
->for the power to the motor - you can use any old phone charger (or other tipe of ellectric power transformer)

-how does it work :
-first everithing must be in a box to be totaly dark inside
- when the phone receives the video call, -> the screen lights up
-> the sensor sees the light and activates the motor
-> which tries to spin, but it only pushes a little bit the little solid metal bar -> which puches the answer button
-> and you stick the box where ever you want the phone insaid to see (and show you)

- OK - how you build it - that's for everyone imagination to change - you buy a solar garden lamp (probably 1-2 $ ) - they all have a light sensor - you soulder a little electric motor to the terminals that lights up the LED (in the night time) [the thing is (and i don't konw exacly how it works) you will have to solder contacts inversed - or inver the contacts to the light sensor] - i don't know for sure - but you need the sensor to start the engine when is light not when is dark (as it does normaly) - and then you soulder again some kind of little stick (bar) of metal - to the head of the motor and positioned straight to the ansering button of the phone (in order to push the button when the motor tries to spin) - and thats the more complicated part - - now you will have to place the hole phone in an perfectly light sealed carboard box (with the execpt of the little camera, which needs to see outside ofcorse -you make the configuration to 3G network for both phones - in order to have a video call betwen them -how does it work - when the phone receives the video call, -> the screen lights up -> the sensor sees the light and activates the motor -> whic tries to spin, but it only pushes a little bit the little solid metal bar -> which puches the answer button
gary.kam4 years ago
can u plz mail me its schematics on (kam_gary@yahoo.co.in)plz.....regards
Ral66394 years ago
Has anyone had any luck using the usb port on the mobile phone to communicate serial codes from the microprocessor? just a thought to clean up the design....
bk-paradox5 years ago
You can use a mosfet instead of the relays if you wanted to make it smaller. When the mosfet is on it is considered shorted with 1 ohm generally resistance. transistor wouldn't work due to current needing to flow. I like this concept alot.. taking existing hardware and modifying it for a new project. Lots of cheap cellphones around for projects like these. Thanks for the inspiration
tanntraad (author)  bk-paradox5 years ago
Will give those mosfet's a go. I had some problems with the key pad matrix since you can't have a common ground.
The way the keypad matrix work is just shorting the 2 pads together using graphite which is in the key.. so by soldering a wire to each pad and then connecting one wire to drain the other to source.. applying voltage to the gate of an N channel enhanced mosfet will then connect the two pads ^_^ hope it works for you. Haven't done it for cellphones but have done similar for other projects
tanntraad (author)  bk-paradox5 years ago
It's a bit more complex than that on the phones I've been working on. The Nokia I'm working on now (old 3310) has 5 negative and 4 positive rails in the matrix. This gives up to 20 different keys, the Nokia has 16. E.g. connecting two or more negative rails together won't work. I think there must be some kind of pulsed/ switched mode matrix. Any info is welcome!
How do you think it detects the key press it connects 2 pads or columns and rows.
You are talking about DTMF keypad most likely Basically you have 4 rows and 4 columns (3 columns for a standard phone 4 for a test phone) and each one produces a frequency so when you press 1 you get a tone of 697 Hz mixed with 1209 Hz which tells the controller that you pressed that button.. So with 7 pins you can control the whole keypad or just send a tone using an ic which would be another viable option
a pic of a dtmf decoder

Hope this is the same as you are talking about?
Buy a keypad from an electronic store and see how it detects a press ^_^
tanntraad (author)  bk-paradox5 years ago
Some more info on the phone; On the 3310, each pad consists of a ring with a dot in the middle. It's got 4 rails of positive rings(lets call them columns from A to D), and 5 rails of negative center dots (rows from E to I). Connecting any column with any row produces a single unique value e.g."7" or "Menu" or "Arrow up". This I have tested. Any keystroke can be replicated by combining a column and a row. Connecting two negative rails and one positive rail will NOT work and no value will be produced. This is why transistors have failed. Measuring with a multimeter shows equal potential between all pos. and neg. Without an oscilloscope I can not be sure, but I suspect a pulsed mode matrix. The concept is this; Column A, B, C, and D are switched on and off sequentially. For each column, every row (E, F, G, H, I) is switched on and off in the same way. For example; Column B: ON Row E ON Row E OFF Row F ON Row F OFF ... ...etc.... Column B OFF This looping must of course occur very fast as not to miss any key strokes. Will try to use a micro with A, B, C, D as inputs and E, F, G, H, I, as outputs. The micro will then only turn on E to I when the appropriate input is on. Basically I don't know what kind of matrix this is but I'll try to find out. A regular keypad (like the one I'm holding in my hand now, http://www.acroname.com/robotics/parts/R257-3X4-KEYPAD.html ) can be used in MANY different ways including DTMF, resistive, pulsed, or by using diodes.
an npn or pnp would fail because you need current flowing in order to use it as a switch which means the emiiter would have to be connected to ground so current can flow An enhanced mosfet on the other hand only requires a potential difference e.g. voltage potential to switch Have a look at the keypad matrix below it is from 3310. I think you got yourself confused.it's pretty standard Got to keep in mind all you do when you press any button is connect things together don't see how you can make it more complicated. but thats just my 2 cents.
nokia 3310 keypad.png
tanntraad (author)  bk-paradox5 years ago
Thanks for the image!  You got a lager one or a link maybe? Can't really tell out the details from that one:) Still haven't tried the mosfet's but I'm going to. Can you advise me (with a schematic) on how to connect them? I just can't see how it would work but maybe I'm missing something:)
Is this the kind? http://upload.wikimedia.org/wikipedia/en/7/7b/Enhancement-MOSFET-symbols.png

tanntraad (author)  tanntraad5 years ago
Note to my image: The micro can be powered by the phone's battery if needed. Using one transistor on a single key works great but the real problem arises when you connect two or more keys. I really hope you could advise me on how to connect the MOSFET's as I can't figure out how to avoid mixing up the matrix.
tanntraad (author)  tanntraad5 years ago
I found that schematic on http://www.anysvc.net/downloadcenter/down/200509/20050916180492.pdf I snippet out a section where the diodes are. It's too late (4 AM here) for me to test now but think I'm on to something. I suspected diodes somewhere but didn't know where (hard to measure "in the blind"). I made a diagram last week from the reverse engineering and it matches (except the diodes ). Will post my findings tomorrow.
Good to see you are a searcher ^_^
There are two ways to tackle this as I said before one is mosfet directly on the keys the other is an IC such as the picaxe feeding the key information to the phone.
here is the sample of the mosfet schematics.
Obviously not a full circuit.
When you set the pin high the button is pressed i.e the row and column are connected :)

If you put some logic probes on the rows and columns you can emulate the same on a picaxe or similar microcontroller.
mosfet button.png
tanntraad (author)  bk-paradox5 years ago
Thanks for the reply:) ..But I think you might be misunderstanding my problem. I'm very familiar with the basics of electronics, and then some. My real problem is connecting MORE than one transistor/ Mosfet. According to your picture, a potensial is applied to the gate and source. This is fine for one mosfet and it will work. Now, when you've got two mosfet's, the problem is that Source on both is connected to ground. The mosfet's will work just fine but the matrix is lost. Separating the ground is key to making this work. Now, thanks to you pointing me to that Nokia schematic I think the solution is as simple as adding a few diodes (source to ground). Will try it as soon as possible. Also from the schematic it is clear that it is not a pulsed matrix but rather a set of diodes separating what they label as rows. I really need to get an oscilloscope at home, but then again, reverse engineering can be fun also :)
Could I then suggest 1 alot more elegant approach just use 1 chip directly connected to the columns and row and using an oscilloscope which you can use your soundcard for (cheap but effective sometimes) and work out the signalling.
I would make a bold assumption and say it is dtmf because it's a phone. So then a picaxe to send that freq should work and would be very small indeed. Just got to make sure you have the right logic levels etc.
I think we both misunderstood each other lol ^_^
look forward to seeing what you come up with, as I'm overseas atm and can't do my own write up.
tanntraad (author)  bk-paradox5 years ago
That's my next step. Those diodes bug me. At the moment I can't see any other solution than emulating. That, or going back to relays. They are bulky but they sure work flawlessly every time ;)
Can you upload your schematic please..
tanntraad (author)  bk-paradox5 years ago
Are you thinking about the 3310 or the SE in the instructables? I don't have the schematic for the SE but it is pretty strait forward. When I succeed with the Nokia, I'll post the schematics for sure:)

PS; I tried an audio card oscilloscope but it was too much noise to pick up anything..
Already got the 3310 was talking about the instructable..
Was going to copy your schematic and port it to the mosfet so you can see
how a mosfet can replace a relay but meh..
tanntraad (author)  bk-paradox5 years ago
That would be awesome. As far as I remember, the SE worked in the same way. never scoped it either but it wouldn't be required if you went with mosfets. Can you do a quick schematic? E.g four buttons, maybe spanning across three rows and four columns or something like that. I'd really appreciate it! Would save me a lot of time. I guess you're planning on using diodes also?

The best would be if the micro and phone had their separate batteries(so one can adopt the schematic into other projects without worrying about different voltages) but I don't know if that works? I can give you a general schematic on how I interface with relays; (I did it like that so that others can join in on the discussion if they want:) )
Thats what I figured it would be...

Here is an image I found which shows what I was trying to say unsuccessfully

You can drive the mosfet with the logic level of a picaxe just got to read the
data sheet

tanntraad (author)  bk-paradox4 years ago
Great picture! Here's one more of my really bad MSpaint pictures;) Is this what you're thinking? 

they can share a common source that won't affect it at all.
Especially seeing as how you can only press one button at a time.
It acts exactly as a relay but instead of being open it just has a ridiculously high
impedance which for all intensive purposes is open.

Try it out with 1 button then chuck in the other should work fine.

I don't see trouble with it at all.

Really wish I was home at my workbench >_< lol

If you want I can find a suitable mosfet for this purpose

Would love to see this in smd form would be impresive could fit in the battery compartment and would be for all purposes just a phone to any1 seeing it
tanntraad (author)  bk-paradox4 years ago
As I've said before, the mosfet's will work but the key pad will not. Adding diodes might work..
Ahhh I see I did say common source >_< my mistake your fault lol :)
tanntraad (author)  bk-paradox4 years ago
So, does anyone have a solution for this problem? Maybe I should do a post in the forums..
You've confused your diagram..
if you look at the relay your coil has a common source..
A mosfet doesn't need that.. as it only had 3 inputs not 4
I guess you are a picture person so here you go
tanntraad (author)  bk-paradox4 years ago
No I haven't.
I drew it like that so others could see the consept. I can draw in the symbols for mosfets but it will still be exactly the same.

 Again; you need to draw the COMPLETE schematic. You are only drawing the POSITIVE output on the microcontroller. The microcontroller has a negative (ground) right? Draw it in! Then you'll see. Remember that you'll have to have a potential difference to turn the mosfet on. That means that the positive output has to have a negative somewhere. 

Also what you have there on the right is just two simple switches. That's easy and everybody agrees that just turning on some switches is easy . you need to draw a MATRIX of switches. Then you'll have a problem.
I'll try again:

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