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FM Transmitter Circuit Diagram - Xtal Locked, Crystal Controlled - 1/2 Watt

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1/2 Watt Body Bug - Crystal Controlled - BBG ( NBFM )
Resistors: 1/4 Watt
R1 = 10K
R2 = 1 MEG
R3 = 22K
R4 = 1 MEG
R5 = 22K
R6 = 100 Ohm
R7 = 10K
R8 = 100K
R9 = 10K
R10 = 150 Ohm
R11 = 100K
R12 = 10 Ohm
R13 = 150 Ohm ( 1/2 Watt Resistor On This One )
R14 = 2.2K
R15 = 10 Ohm ( 1/2 Watt Resistor On This One )
R16 = 3.3K
R17 = 47 Ohm ( 1/2 Watt Resistor On This One )

Capacitors: - Disc Or Electrolytic ( Electrolytic Shown with +/- ) 
All Low Voltage
C1 = .02 ( Two .01s in Parallel )
C2 = .001
C3 = .01
C4 =  4 to 20 Pf Trimmer ( Adjustable ) Small Surface Mount Type
C5 = 10 pf
C6 = 100 pf
C7 = 100 pf
C8 = .01
C9 = 4 to 20 Pf Trimmer ( Adjustable ) Small Surface Mount Type
C10 = .01
C11 = 4 to 20 Pf Trimmer ( Adjustable ) Small Surface Mount Type
C12 = .01
C13 = 4 to 20 Pf Trimmer ( Adjustable ) Small Surface Mount Type
C14 = .001
C15 = 4 to 20 Pf Trimmer ( Adjustable ) Small Surface Mount Type
C16 = 4 to 20 Pf Trimmer ( Adjustable ) Small Surface Mount Type
C17 = .001
C18 = 4 to 20 Pf Trimmer ( Adjustable ) Small Surface Mount Type
C19 = .01
( SPECIAL CAPACITOR ) There is A Capacitor Connected across R13 that is not shown in the
schematic: This cap is a standard .01 Disc

Transistors:
Q1 and Q2 = PN918 NPN
Q3 = 2N3866 NPN
Q4 = PN2222 NPN
Q5 and Q6 =  2N3866 NPN                           

VR:
NTE-613 Varactor Diode or a suitable replacemen.t

ON/OFF Switch:
Any, On / Off Switch Will Do - connecting the + side of the 9 volt battery to the circuit

BATTERY:
9 Volts D.C. The Negative Side Of The Battery Connects To The On/Off Switch to ground

M1:
Most any electret element will do. Digikey electronics does sell some very small and sensitive ones.

L1, L2, and L3 Below: See Wound Samples On The Right Hand
Side Of This Page - for winding all coils in this circuit.

L1:
21 Turns of # 30 Magnet Wire Wound tight on a Digi-Key Electronics ( Catalog Listed On The
Internet )  3368K-ND Fiber Washer. The Inductance Of This Coil Is .150 uH

L2 and L3:
14 Turns of # 24 Magnet Wire Wound tight on a Digi-Key Electronics ( Catalog Listed On The
Internet ) #3368K-ND Fiber Washer. The Inductance Of This Coil Is .07 uH

Antenna:
18 1/2 Inches of small flexible stranded wire

XT: ( CRYSTAL )
I usually build this circuit to operate between 150 to 165 Mhz. The Crystals I use Are The Digi-Key
Electronics ( Catalog Listed On The Internet ) Barrel Crystals CA-301 Type which cost a couple of
bucks per crystal. This circuit uses a X5 Multiplier and then a X2 Multiplier In the Final.

Example: If I use a 15 Mhz Barrel Crystal, the frequency at Q4s output is: Xtal X 5 Or: 75 Mhz into
Q5. Q5 Multiplies 75 Mhz X 2 for an end frequency out of the final Q6 ( Desired Output Frequency )
of 150.00 Mhz.

Virtually any Fundamental Crystal between 14 and 17 Mhz will output a frequency of between 140 to
170 Mhz, if the crystal has a load capacitance of around 18 pf. If you wish to build this transmitter
on A custom frequency simply use the X5 X2 formula below and order a custom cut crystal
specifying an 18 pf CL.

Example: My Customer Desires this transmitter to function at an output frequency of: 158.250 Mhz?
( 1 ) Divide 158.250 times 2. This Equals 79.125
( 2 ) Divide 79.125 times 5. This Equals 15.825
I would order the crystal at a Fundamental frequency of 15.825 Mhz, tolerance of .001% and a
Crystal Load Capacitance of 18 pf. When I tune my transmitter, my output transmit frequency would
be: 158.250 Mhz.




All Electronic Components - Digi-Key Electronics
The BBG Body Transmitter schematic shown below has been one of the most "Sought After" circuits I have ever Produced. It was in fact - THE flagship product of my original company and a product that I manufactured and sold from the middle 80s until early 2006. I no longer produce this device since I am retired now and no longer have to hump-it for a living.

I produced and sold thousands of these units - and they were sold to virtually every branch of governmental agency that you could dream up. It was originally produced as a model BB2, and over the past 25 years, only the stock number has changed, now known as the BBG. An original photo is shown below.




















I Have The BBG FM Transmitter Circuit up in several places on the net. I could not count the amount of emails I receive every year from not only Law Enforcement Agencies who build  it with various questions, but also from a wide variety of other folks including - experimenters, electronic builders, hobbyist and RF buffs.

Some Have Tried To Re-Engineer The Wheel by changing its circuitry, some have used transistors and components other than what's called for in the circuit and whatnot. All have one thing in common. "Problems" in their emails! My response has always been - build it as stated, with the components as stated and it will function as stated.

To Avoid any Future Problems, to those who wish to tackle and build this unit,  I am releasing a Full Workup, of its layouts that you will find below . These templates are in fact The Masters I used in building over 6,000 of these units over 25 years.
                                            
                                            Enjoy, John S. Wilson Jr
.



Digi-Key Electronics 3368k-nd
fm transmitter circuit coils
The Images shown below are actually much larger than the actual forms.
Actual Inside Dia: 0.120" (3.05mm)
Actual Outside Dia: 0.250" (6.35mm) 1/4"
Actual Thickness: 0.062" (1.57mm)
Digi-Key Electronics 3368k-ND Coil Form Samples Shown Above
Unwound
Wound
fm transmitter circuit - crystal controlled, vhf
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