cellphone detector circuit - Electronic Circuits Projects Diagrams Free

colmcuddy · 15th July 2008, 01:07 AM

Looking for simple cellphone detector circuit

audioguru · 15th July 2008, 02:43 AM

Today it is difficult to detect cell phones because they use many frequency bands.
10 years ago it was easy because they used only a single frequency band.
I think they use "spread spectrum" now so it is very difficult to detect.

If your sensor is very close then it can pick up the 2W of RF power easily.

RadioRon · 15th July 2008, 07:03 AM

First make a dipole antenna tuned to 1800 MHz. Then attach an additional dipole, tuned to 900 MHzto the same coaxial line at right angles to the 1800 MHz antenna. Next, attach the other end of the coaxial line to a printed circuit board containing a circuit based on this IC:
http://www.analog.com/static/importe...ets/AD8362.pdf

The output of this circuit can be connected to a DC voltmeter, an oscilloscope or to any sort of display system that has a voltage input. Some of the voltages detected may be short duration so you may have to add a simple peak hold circuit or pulse extender to the output.

This circuit may detect most cellphone signals with varying range, perhaps limited to about 15 feet or so. If more range is required, it is possible to add a preamplifier with a set of bandpass filters that increases the sensitivity, but this addition becomes difficult to do.

Sceadwian · 15th July 2008, 03:30 PM

Mind you if you point something that looks like that at a cell phone user they're probably going to move away from you very fast so the effective range will be significantly less than 15 feet =)

What do you want to 'detect' a cell phone for? I'm guessing for security?

colmcuddy · 16th July 2008, 12:24 AM

Need circuit for college project, mobile phone detector product design...
Cheers for help folks..

From your irish friend...

Torben · 16th July 2008, 06:56 AM

What is the actual assignment? If designing the thing *is* the assignment, and we design it for you, do we get the mark?

Torben

transistance · 16th July 2008, 01:25 PM

Voltage Labs had made a GSM detector with direction of source sensitivity like 4 years ago. But they had to shutdown the site when the guys started building/publishing gyroscopic, electromagnetic and sonar non-lethal weapons.

Although I was sure that with good aiming and some modification you could kill people by using his gyroscopic and EM weapons.

Well... so good luck contacting them or people who have archived their schematics and tutorials!

Or.. you can start researching for your project from GSM jammers and develop your idea from there..

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15th July 2008, 01:07 AM	#1
colmcuddy	cellphone detector circuit Looking for simple cellphone detector circuit

15th July 2008, 02:43 AM	#2
audioguru	Today it is difficult to detect cell phones because they use many frequency bands. 10 years ago it was easy because they used only a single frequency band. I think they use "spread spectrum" now so it is very difficult to detect. If your sensor is very close then it can pick up the 2W of RF power easily. __________________ Uncle $crooge

15th July 2008, 07:03 AM	#3
RadioRon	First make a dipole antenna tuned to 1800 MHz. Then attach an additional dipole, tuned to 900 MHzto the same coaxial line at right angles to the 1800 MHz antenna. Next, attach the other end of the coaxial line to a printed circuit board containing a circuit based on this IC: http://www.analog.com/static/importe...ets/AD8362.pdf The output of this circuit can be connected to a DC voltmeter, an oscilloscope or to any sort of display system that has a voltage input. Some of the voltages detected may be short duration so you may have to add a simple peak hold circuit or pulse extender to the output. This circuit may detect most cellphone signals with varying range, perhaps limited to about 15 feet or so. If more range is required, it is possible to add a preamplifier with a set of bandpass filters that increases the sensitivity, but this addition becomes difficult to do. __________________ RadioRon Last edited by RadioRon; 15th July 2008 at 07:05 AM.

15th July 2008, 03:30 PM	#4
Sceadwian	Mind you if you point something that looks like that at a cell phone user they're probably going to move away from you very fast so the effective range will be significantly less than 15 feet =) What do you want to 'detect' a cell phone for? I'm guessing for security? __________________ "Because I be what I be. I would tell you what you want to know if I could, mum, but I be a cat, and no cat anywhere ever gave anyone a straight answer, har har."

16th July 2008, 12:24 AM	#5
colmcuddy	Need circuit for college project, mobile phone detector product design... Cheers for help folks.. From your irish friend...

16th July 2008, 06:56 AM	#6
Torben	What is the actual assignment? If designing the thing is the assignment, and we design it for you, do we get the mark? Torben __________________ Curiosity was framed. Ignorance killed the cat.

16th July 2008, 01:25 PM	#7
transistance	Voltage Labs had made a GSM detector with direction of source sensitivity like 4 years ago. But they had to shutdown the site when the guys started building/publishing gyroscopic, electromagnetic and sonar non-lethal weapons. Although I was sure that with good aiming and some modification you could kill people by using his gyroscopic and EM weapons. Well... so good luck contacting them or people who have archived their schematics and tutorials! Or.. you can start researching for your project from GSM jammers and develop your idea from there.. __________________ transistance is futile... Last edited by transistance; 16th July 2008 at 01:25 PM.