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RF transmitter circuit

freakinshoe69

Sep 20, 2017
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I want to build a bug to that transmits on a frequency that I can pick up on my portable police scanner. Like a baby monitor. Ive google the crap out of it and cant find anything conclusive any and all help would b appreciated. This is for my own house.
 

davenn

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Sep 5, 2009
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I want to build a bug to that transmits on a frequency that I can pick up on my portable police scanner. Like a baby monitor. Ive google the crap out of it and cant find anything conclusive any and all help would b appreciated. This is for my own house.

all the common ones transmit in the FM band between 88 and 108 MHz
there's zillions of ccts on the net for them
 

73's de Edd

Aug 21, 2015
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SIR freakinshoe69 . . . . .


Could we suggest . . . for utter simplicity . . . . . none other than a a baby monitor transmitter . . . . . . .acual DC supply power is usually 9VDC.
Availability . . . as used item . . from . . .
Yard sales . . . . Garage sales . . . . Flea markets . . . .Schindlers . . OOOps . . .Craigs list . . .
Typically 1-5 bux used.

E -bay
https://www.ebay.com/sch/Baby-Monitors/20435/i.html?_from=R40&_nkw=used+baby+monitors&_sop=15


IF you still just INSIST on building GOGGLE UP modulated FM transmitter circuits and . . . . . thatsalookalikea . . ..

POST GOOGLIFIED:
https://www.google.co.in/search?tbm=isch&slpassthru=1&q=Modulated Fm Transmitter Circuits
( NOTICE
. . . one circuit per customer . . . . . limit.)

73's de Edd
 

freakinshoe69

Sep 20, 2017
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thanx for the help, i am new to this and and didnt know exactly what i needed to google
 

73's de Edd

Aug 21, 2015
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SIr freakinshoe69 . . . . .

If this is being it . . . .

https://www.amazon.com/DIY-Wireless...506277963&sr=8-10&keywords=fm+transmitter+kit

Hmmmmmmmmmmm looks like they are giving you two units . . .

Looks like its construction and following testing / evaluation will be an initial Baptismal under fire for you on RF oriented electronics..
The meager 3V power may give 10-15 ft range . . . with you having to try it to exactly see .
Also the simple circuit will be subject to hand capacitance / handling in a detuning of the operating frequency, so set up the "bug ?" into its fixed hiding place and tune in to its related frequency WHEN distanced away from the unit..

The length of wire used as the transmit antenna . . .connected onto C7 will have an effect on range . . .initially, watch what info they suggest .
Since a short 6 inches is inadequate. . .but 25 feet is an INSANELY unrealistic assumption . . . that length would work even BETTER..

Also the signal propogation at the 108 high end of the FM band is better than the 88 low end, and at that 108MC end . . . a straight vertical wire antenna of ~36 inches length would be in order..

73's de Edd
 
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