FM Telephone Transmitter Circuit

FM Telephone Transmitter Circuit - Xtal Locked - VHF

Although Low Powered, this crystal controlled, crystal locked FM telephone transmitter circuit mounted up on the pole, or at an elevated location, the signal will transmit both sides of the telephone conversation for miles. Limited distance at ground level ( Around a couple of hundred feet ) at the most. Sends out a continual blank fm transmitter carrier signal when the target phone is on the hook so easy to lock onto with a vhf receiver scanner. A very stable telephone transmitter circuit.

FM Telephone Transmitter Circuit - TP1
© 2011 By John S. Wilson Jr.
john@bugplan.com
                                                                   

Parts List: Circuit # TP1, Telephone Transmitter Circuit
Xtal, Crystal Controlled FM

Resistors: 1/4 Watt
R1 = 10K Pot ( Trimmer Resistor )  - For Modulation / Deviation Adjustment
R2 = 220 Ohm
R3 = 10K
R4 = 470 Ohm
R5 = 33K
R6 = 4.7K
R7 = 100 Ohm
R8 = 10K
R9 = 10K
R10 = 100K
R11 = 22K
R12 = 100K
R13 = 22K
R14 = 1 MEG
R15 = 1 MEG
R16 = 2.2K
R17 = 1 MEG
R18 = 47K

Capacitors: - Disc Or Electrolytic ( Electrolytic Shown with +/- )  All Low Voltage
C1 = 4.7 MFD
C2 = .01
C3 = 100 pf
C4 = .001
C5 = 2 to 22 pf Trimmer ( Adjustable ) Small Surface Mount Type
C6 = 10 pf
C7 = .001
C8 = 18 pf
C9A = 2 to 22 pf Trimmer ( Adjustable ) Small Surface Mount Type
C9 = 10 pf
C10 = .01
C11 = .001
C12 = 2 to 22 pf Trimmer ( Adjustable ) Small Surface Mount Type
C13 = 100 pf
C13A = 2 to 22 pf Trimmer ( Adjustable ) Small Surface Mount Type
C14 = .01
C15 = .01
C16 = .01
C17 = .001
C18 = .001
C19 = .001

Transistors:
FET1 = MPF-102 - Digi-key Electronics
Q7, Q6,  Q5, and Q1 = 2N3904 - Digi-key Electronics
Q2, Q3, And Q4 = BFS17 - Digi-key Electronics

VR:
NTE-613 Varactor Diode or a suitable replacement such as the Digi-key Electronics MV2107

ON/OFF Switch:
Any, On / Off Switch Will Do - connecting the + side of the 1.5 volt battery to the circuit

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

L1 Thru L4:
14 Tight turns of # 24 Magnet Wire, wound around A Digi-key Electronics 3368K-ND Fiber Washer

Antenna:
18 Inches of small flexible stranded wire

XT: ( CRYSTAL )
Use any crystal between 14 to 17 Mhz. The output transmit frequency is your xtal frequency X 10. For Example, if you desire an output frequency of 160.0 Mhz, you would use a 16 Mhz Crystal. Your crystal should have a crystal load capacitance of around 18 pf. I use Barrel Crystals ( Digi-Key Electronics Type CA-301 in this circuit. Adjust the 10K Pot feeding the Crystal/Varactor Diode for best modulation/Deviation

Clip 1 and Clip 2:
Small Alligator Clips. Clip to The Red and Green Wires Of The Telephone line, in the basement, along the wires, at the jack in a room - Or wherever, as long as you clip into the red and green wires on the telephone line

 

FM Telephone Transmitter Circuit # TP1

Crystal Controlled FM Telephone Transmitter Circuit - TP1

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