3 W FM TRANSMITTER

Parts

Part	Total Qty.	Description	Substitutions
R1,R4,R14,R15	4	10K 1/4W Resistor
R2,R3	2	22K 1/4W Resistor
R5,R13	2	3.9K 1/4W Resistor
R6,R11	2	680 Ohm 1/4W Resistor
R7	1	150 Ohm 1/4W Resistor
R8,R12	2	100 Ohm 1/4W Resistor
R9	1	68 Ohm 1/4W Resistor
R10	1	6.8K 1/4W Resistor
C1	1	4.7pF Ceramic Disc Capacitor
C2,C3,C4,C5,C7,C11,C12	7	100nF Ceramic Disc Capacitor
C6,C9,C10	3	10nF Ceramic Disc Capacitor
C8,C14	2	60pF Trimmer Capacitor
C13	1	82pF Ceramic Disc Capacitor
C15	1	27pF Ceramic Disc Capacitor
C16	1	22pF Ceramic Disc Capacitor
C17	1	10uF 25V Electrolytic Capacitor
C18	1	33pF Ceramic Disc Capacitor
C19	1	18pF Ceramic Disc Capacitor
C20	1	12pF Ceramic Disc Capacitor
C21,C22,C23,C24	4	40pF Trimmer Capacitor
C25	1	5pF Ceramic Disc Capacitor
L1	1	5 WDG, Dia 6 mm, 1 mm CuAg, Space 1 mm
L2,L3,L5,L7,L9	5	6-hole Ferroxcube Wide band HF Choke (5 WDG)
L4,L6,L8	3	1.5 WDG, Dia 6 mm, 1 mm CuAg, Space 1 mm
L10	1	8 WDG, Dia 5 mm, 1 mm CuAg, Space 1 mm
D1	1	BB405	BB102 or equal (most varicaps with C = 2-20 pF [approx.] will do)
Q1	1	2N3866
Q2,Q4	2	2N2219A
Q3	1	BF115
Q5	1	2N3553
U1	1	7810 Regulator
MIC	1	Electret Microphone
MISC	1	PC Board, Wire For Antenna, Heatsinks

BOSTER FM 30 Watt

PARTS

C1, C2, C3, C4 = 10 -80pF

C 5 = 10nF

C6 = 1000pF

C7 = 100nF

C8 = 2200mF/35V

L1 = 1 coil with diameter of 10 mms, 1 mm

L2 = 7 coils with diameter of 10 mms, 0,8 mm

L3 = 3 coils with diameter of 10 mms, 1 mm

TR1 = BLY89

RFC = RF tsok

4 W FM TRANSMITTER

This is a small but quite powerful FM transmitter having three RF stages incorporating an audio preamplifier for better modulation. t has an output power of 4 Watts and works off 12-18 VDC which makes it easily portable. It is the ideal project for the beginner who wishes to get started in the fascinating world of FM broadcasting and wants a good basic circuit to experiment with.

Modulation type: ........ FM
Frequency range: .... 88-108 MHz
Working voltage: ..... 12-18 VDC
Maximum current: ....... 450 mA
Output power: ............ 4 W

Electronic Diagram.

Parts List

R1 = 220K
R2 = 4,7K
R3 = R4 = 10K
R5 = 82 Ohm
R = 150Ohm 1/2W x2 *
VR1 = 22K trimmer

C1 = C2 = 4,7uF 25V electrolytic
C3 = C13 = 4,7nF ceramic
C4 = C14 = 1nF ceramic
C5 = C6 = 470pF ceramic
C7 = 11pF ceramic
C8 = 3-10pF trimmer
C9 = C12 = 7-35pF trimmer
C10 = C11 = 10-60pF trimmer
C15 = 4-20pF trimmer
C16 = 22nF ceramic *

L1 = 4 turns of silver coated wire at 5,5mm diameter
L2 = 6 turns of silver coated wire at 5,5mm diameter
L3 = 3 turns of silver coated wire at 5,5mm diameter
L4 = printed on PCB
L5 = 5 turns of silver coated wire at 7,5mm diameter

RFC1=RFC2=RFC3= VK200 RFC tsok

TR1 = TR2 = 2N2219 NPN
TR3 = 2N3553 NPN
TR4 = BC547/BC548 NPN
D1 = 1N4148 diode *
MIC = crystalic microphone

STEREO FM TRANSMITTER

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CIRCUIT BOARD Dimensions of the PCB should be 57 mm x 35 mm (W x H).

FM TRANSMITTER 0,4 W

Power supply: 12-14 V stab., 100 mA
RF power: 400 mW
Impedance: 50-75 ohm
Frequency range: 87,5-108 MHz
Modulation: wideband FM

Schematic diagram

Parts list

Capacitors:
C1, C2, C12 - 100 pF (ceramic)
C3, C5 - 0,22 uF (electrolytic)
C4 - 1,8 nF (plastic)
C13, C16, C17, C19 - 1 nF (ceramic)
C8, C9 - 10 pF (ceramic)
C10 - 47 pF (ceramic)
C11 - 8,2 pF (ceramic)
C14 - 60 pF trimmer
C15 - 35 pF trimmer
C18, C7 - 100 nF (ceramic)
C20 - 470 uF (electrolytic, 16 V)

Coils:
(All coils are free-standing air-core types, wound of 0,7 mm Cu wire, 6 mm internal diameter.)
L1 - 4,5 coils
L2 - 9,5 coils
L3 - 4,5 coils

Resistors:
R1, R2 - 10 k pot.
R3 - 33 k
R4, R7, R12 - 10 k
R5, R11 - 470
R6 - 27 k
R8 - 22 k
R9 - 270
R10 - 100

Misc.:
D1 - BB409 (BB109G, BBY31) varicap
T1 - BC547C (BC548C, BC547B)
T2 - BFR91A (BFR96)
T3 - BFR96

Antenna
Power supply
3,5 mm jack
CD player, computer
6 V / 0,1 A bulb

PCB LAYOUT

PLL FM TRANSMITTER 1W

This small FM transmitter includes a limiter, a microphone amplifier and a PLL digital tuning. All the parts are placed on one circuit board. The RF power is switchable between 1 W (HI) and 0,2 W (LO).

Technical specifications

Supply voltage: 12 V from accumulator or regulated power supply
Supply current (HI/LO): 270/170 mA
RF power HI: 1 W
RF power LO: 0,2 W
Impedance: 50-75 ohm
Frequency range: 87,5-108 MHz
Modulation type: wide-band FM
Modulation inputs: line, mic, RDS/MPX
PCB dimensions: 11,3 x 8,8 cm

RF part 1 W

Resistors:
R1 - pot. 5 k
R2, R12 - 1 k
R3 - 220
R4, R8, R10 - 27 k
R5, R6, R14, R17 - 10 k
R7, R16 - 470
R9 - 100
R11 - 270
R13 - 10
R15 - 22 k

Capacitors:
C1 - 4,7 uF
C2 - 1 uF
C3, C4, C12 - 100 pF
C6, C9, C11, C13, C14, C19, C22 - 1 nF
C7, C8 - 10 pF
C10 - 8.2 pF
C18 - 22 pF
C15 - trimmer 47 pF
C16, C17 - trimmer 60 pF
C20, C5 - 100 nF mini
C23 - 470 uF

Coils:
(All coils are free-standing air-core types, wound of 0,7 mm Cu wire, 6 mm internal diameter.)
L1 - 4,5 coils
L3 - 2,5 coils
L4 - 1,5 coils
L2 - 6,5 coils around R9 resistor
L5 - 9,5 coils
L6 - 5,5 coils
L7 - 3,5 coils

Diodes:
D1, D2 - BB109G, BBY31 or BB409

Transistors:
T1 - BC547C (BC548C, BC547B)
T2 - BFR91A (BFR96)
T3 - BFR96
T4 - 2SC1971

Misc:
S1 - switch

PLL digital tuning

Resistors:
R31 - 1k
R32 - 4k7
R33, R37 - 10k
R34, R35 - 1k
R36 - 470
R38 - 47k

Capacitors:
C31, C42 - 2,2 nF
C32, C40 - 10 nF
C33 - 47 uF
C34 - 10 uF tantal
C35 - 0,47 uF
C36, C41 - 100 nF
C37 - 1 nF
C38 - 220 uF
C39 - 22 pF

Misc:
IC31 - SAA1057
IC32 - PIC16F84-04 + socket
IC33 - 78L05
X31 - 4 MHz crystal
D31 - LED diode
Tl31 - button
Jumpers 2x8 pins or DIP switches

Audio and power supply part

Resistors:
R51, R52 - pot. 5 k
R53, R58, R64 - 10 k
R54, R55 - 22 k
R56 - 56 k
R57 - 1,5 k
R59 - 180 k
R60 - 820
R61 - 10 M
R62 - 47
R63 - 240 k

Capacitors:
C51, C54 - 100 pF
C52, C57 - 2,2 uF
C53 - 1 uF
C55, C62, C63 - 10 uF
C56, C64 - 47 nF
C58 - 1 nF plastic
C59, C60 - 1 uF tantal 25 V
C61 - 100 uF
C65 - 150 nF
C66, C67, C68, C70 - 10 nF
C69 - 470 uF

Misc:
T51 - BF245C
T52 - BC556B
IC51, IC52 - LM386
S51 - switch

Complete parts list

Resistors:
1x 10
1x 47
1x 100
1x 270
2x 220
3x 470
1x 820
5x 1k
1x 1,5 k
1x 4,7 k
9x 10 k
3x 22 k
3x 27 k
1x 56 k
1x 47 k
1x 180 k
1x 240 k
1x 10 M
3x pot. 5 k log.

Capacitors:
1x 8,2 pF
2x 10 pF
3x 22 pF
5x 100 pF
8x 1 nF
1x 1 nF plastic
2x 2,2 nF
5x 10 nF
2x 47 nF
4x 100 nF mini
1x 150 nF
1x 0,47 uF
2x 1 uF
2x 2,2 uF
1x 4,7 uF
4x 10 uF
1x 47 uF
1x 100 uF
1x 220 uF
2x 470 uF
2x 1 uF tantal
1x 10 uF tantal
1x trimmer 47 pF
2x trimmer 60 pF

Semiconductors:
1x BC547C (BC548C, BC547B)
1x BFR91A
1x BFR96
1x 2SC1971
1x BC556B
1x BF245C
2x LM386
1x SAA1057
1x PIC16F84A-04 + socket
1x 78L05
1x Yellow LED 3 mm
2x BB109G, BBY31 or BB409

Misc:
1x 4 MHz crystal
2x switch
1x button
1x jumpers 2x8 pins or DIP switches
1x power supply connector
3x jack 3,5 mm
1x antenne connector
1x plastic case
thin shielded cables

PRINTED CIRCUIT BOARD

MINIATURE FM TRANSMITTER

Parts List
R1,R4,R6 = 10K         C1,C2 = 0.1uF      Q1,Q2 = 2N3904        
     R2 = 1M             C3 = 0.01uF        L1 = 0.1uH
     R3 = 100K           C4 = 4-40pF
     R5 = 100 ohm        C5 = 4.7pF
     R7 = 1K

Construction
This miniature transmitter is easy to construct and it's transmissions can be picked up on any standard FM radio. It has a range of up to 1/4-mile (400 meters) or more, depending on the line-of-sight, obstructions by large buildings, etc. It is great for room monitoring, baby listening, nature research, etc.
L1 is 8 to 10 turns of 22 gauge hookup wire close wound around a non-conductive 1/4-inch diamter form, such as a pencil.
C4 is a small, screw-adjustable, trimmer capacitor.
Set your FM radio for a clear, black space in the lower end of the band (88MHz). Then, with a non-metallic/non-conductive trimmer tool, adjust this capacitor for the clearest reception. A little experimenting and patience may be in order.
Most of the parts values are not critical, so you can try adjusting them to see what happens.

If you decide to substitute transistors with something similar you already have, it maybe necessary adjust the collector voltage of Q1 by changing the value of R2 or R3 (because you change transistors, it changes this bias on the base of Q1). It should be about 1/2 the supply voltage (about 4 or 5v).

Notes
The default for the capacitors type is ceramic, preferably the npo 1% (low noise) type or equivalent. But basically nothing critical here. Use any capacitor you have laying around, but NO electrolytic or tantalum caps. Only if you intend to use this circuit outside the home you may want to select more temperature stable capacitors.

To find the signal on your receiver, make sure there is a signal coming into the microphone, otherwise the circuit won't work. I use an old mechanical alarm clock (you know, with those two large bells on it). I put this clock by the microphone which picks up the loud tick-tock. I'm sure you get the idea... Or you can just lightly tap the microphone while searching for the location of the signal on your receiver.