FM Telephone Transmitter Circuit

FM Telephone Transmitter Circuit - Xtal Locked - VHF

Although Low Powered, mounted up on the pole the signal will transmit both sides of the conversation for miles. Limited distance at ground level ( Around a couple of hundred feet ) at the most. Sends out a continual blank carrier when the target phone is on the hook.

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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