900Mhz/1800Mhz Cellphone detector - Electronic Circuits Projects Diagrams Free

frenchneco · 2nd July 2009, 04:40 AM

My team needs to build a cellphone detector. The 900MHz & 1800Mhz band is being used in our country. Effective radius of detection could be 1 meter - 2 meters. Detection could be in any form (sound, LED, etc)

Does anybody have a working circuit already?
Do we need detect at both frequencies?

Thanks

Papabravo · 2nd July 2009, 02:39 PM

Building circuits to operate in this frequncy rage is both difficult and expensive. It is not for the faint of heart or the weak of wallet. PC boards need to be carefully designed and fabricated with tools that are quite beyond the reach of weekend hobbyists. The test equipment is a whole other story when it comes to expense. You need to find something to buy, unless you light your cigars with $1000 bills. The ones with the picture of Woodrow Wilson that are no longer in circulation.

BTW, commercial radios generally block those frequencies so I think you might be outa luck unless you are a government agency.

frenchneco · 2nd July 2009, 03:33 PM

we saw this ckt in the net. do you think this would work?

Cell phone detector

we assembled it and can't seem to make it work. the 555 is oscillating, the LED is on, and the buzzer is making a very annoying sound. the problem is that the mosfet is not latching.

blueroomelectronics · 2nd July 2009, 03:39 PM

Did you read the comments on that project? Pretty much all looked like this.

Quote:

can u send me detial workig of this circut i am student of QAU. i will be very thankful to u.
Reply

Ahh it's an EFY project, they are generally untested crap.

Quote:

sir im havin problems wid de circuit..de alarm goes off as soon as de circuit is given power..also i wud like to have de design details of de circuit..please help!!!!

frenchneco · 2nd July 2009, 03:52 PM

what's an EFY? awwwwww... anyway it's still bad news for us. we really need help. we're desperate. we only have less than a month to make a project. we badly need WORKING and TESTED projects.

blueroomelectronics · 2nd July 2009, 04:02 PM

Why not choose a project you have knowledge about? What's the point of submitting someone else's work?

EFY = Electronics for You.

frenchneco · 2nd July 2009, 04:13 PM

the problem is we only know little. honestly, we're in a very tight situation right now. we really need all the help now.

blueroomelectronics · 2nd July 2009, 04:15 PM

Quote:

Originally Posted by frenchneco

the problem is we only know little. honestly, we're in a very tight situation right now. we really need all the help now.

How did you get in a tight situation? Did you not show up or study at school?

frenchneco · 2nd July 2009, 04:38 PM

just very bad quality of education man. some schools are just like that. i know we should have done our part. but it's too late now. i hope u understand. sometimes, sh*t just happens.

crutschow · 2nd July 2009, 08:02 PM

Quote:

Originally Posted by frenchneco

we saw this ckt in the net. do you think this would work?

Cell phone detector

we assembled it and can't seem to make it work. the 555 is oscillating, the LED is on, and the buzzer is making a very annoying sound. the problem is that the mosfet is not latching.

Did you lay it out as stated with all component leads as short as possible? At those high frequencies, a careless layout with long leads will not work.

It does not show on the schematic but there should be a 0.01µf decoupling ceramic cap directly across pins 4 and 7 on IC1 (as short leads as possible).

3v0 · 2nd July 2009, 08:26 PM

I wonder what the range for this thing would be if it worked. If it could be setup to respond only to cellphones within 10 to 20 feet I could find a good use for it.

Papabravo · 2nd July 2009, 11:38 PM

Quote:

Originally Posted by crutschow

Did you lay it out as stated with all component leads as short as possible? At those high frequencies, a careless layout with long leads will not work....

I did warn you about this. Remember?
I think you may be SOL. I guess that happens too -- so sorry.

PS I don't think it has the slightest chance of working.

frenchneco · 3rd July 2009, 02:46 AM

Quote:

Originally Posted by 3v0

I wonder what the range for this thing would be if it worked. If it could be setup to respond only to cellphones within 10 to 20 feet I could find a good use for it.

nah. just about 1-1.5 meters.

frenchneco · 3rd July 2009, 02:49 AM

Quote:

Originally Posted by crutschow

Did you lay it out as stated with all component leads as short as possible? At those high frequencies, a careless layout with long leads will not work.

It does not show on the schematic but there should be a 0.01µf decoupling ceramic cap directly across pins 4 and 7 on IC1 (as short leads as possible).

yeah. and we made its pcb as small as possible. tnx for the help mate!

frenchneco · 3rd July 2009, 02:50 AM

Quote:

Originally Posted by Papabravo

I did warn you about this. Remember?
I think you may be SOL. I guess that happens too -- so sorry.

PS I don't think it has the slightest chance of working.

since i'm SOL, could you help me?

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2nd July 2009, 04:40 AM	#1
frenchneco	900Mhz/1800Mhz Cellphone detector My team needs to build a cellphone detector. The 900MHz & 1800Mhz band is being used in our country. Effective radius of detection could be 1 meter - 2 meters. Detection could be in any form (sound, LED, etc) Does anybody have a working circuit already? Do we need detect at both frequencies? Thanks

2nd July 2009, 02:39 PM	#2
Papabravo	Building circuits to operate in this frequncy rage is both difficult and expensive. It is not for the faint of heart or the weak of wallet. PC boards need to be carefully designed and fabricated with tools that are quite beyond the reach of weekend hobbyists. The test equipment is a whole other story when it comes to expense. You need to find something to buy, unless you light your cigars with $1000 bills. The ones with the picture of Woodrow Wilson that are no longer in circulation. BTW, commercial radios generally block those frequencies so I think you might be outa luck unless you are a government agency. __________________ We never have time to do it right; but we always have time to do it over. Last edited by Papabravo; 2nd July 2009 at 02:41 PM.

2nd July 2009, 03:33 PM	#3
frenchneco	we saw this ckt in the net. do you think this would work? Cell phone detector we assembled it and can't seem to make it work. the 555 is oscillating, the LED is on, and the buzzer is making a very annoying sound. the problem is that the mosfet is not latching.

2nd July 2009, 03:52 PM	#5
frenchneco	what's an EFY? awwwwww... anyway it's still bad news for us. we really need help. we're desperate. we only have less than a month to make a project. we badly need WORKING and TESTED projects.

2nd July 2009, 04:02 PM	#6
blueroomelectronics	Why not choose a project you have knowledge about? What's the point of submitting someone else's work? EFY = Electronics for You. __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com/

2nd July 2009, 04:13 PM	#7
frenchneco	the problem is we only know little. honestly, we're in a very tight situation right now. we really need all the help now.

2nd July 2009, 04:38 PM	#9
frenchneco	just very bad quality of education man. some schools are just like that. i know we should have done our part. but it's too late now. i hope u understand. sometimes, sh*t just happens.

2nd July 2009, 08:26 PM	#11
3v0	I wonder what the range for this thing would be if it worked. If it could be setup to respond only to cellphones within 10 to 20 feet I could find a good use for it. __________________ Please post questions to the forums. PM's are for personal communication. BCHS/3v0's Tutorials Junebug USB PIC programmer kit., USB Bit Whacker, The 15 Minute Printed Circuit Board! (+drill time)