Circuit Diagram > 1 Watt Four Stage FM Transmitter

1 Watt Four Stage FM Transmitter

Date: 2012-8-8Author: anonymousReading(214)Collection this page
pcb.hqew.net

This FM transmitter circuit uses four radio frequency stages: a VHF oscillator built around transistor BF494 (T1), a preamplifier built around transistor BF200 (T2), a driver built around transistor 2N2219 (T3) and a power amplifier built around transistor 2N3866 (T4).A condenser microphone is connected at the input of the oscillator. Working of the 1 Watt transmitter circuit is simple. When you speak near the microphone, frequency-modulated signals are obtained at the collector of oscillator transistor T1.

The FM signals are amplified by the VHF preamplifier and the pre-driver stage. You can also use transistor 2N5109 in place of 2N2219. The preamplifier is a tuned class-A RF amplifier and the driver is a class-C amplifier. Signals are finally fed to the class-C RF power amplifier, which delivers RF power to a 50-ohm horizontal dipole or ground plane antenna.

Use a heat-sink with transistor 2N3866 for heat dissipation (Note: or 2N4427 because it works better at 12 V and delivers up to 1 watt RF power). Carefully adjust trimmer VC1 connected across L1 to generate frequency within 88-108 MHz. Also adjust trimmers VC2 through VC7 to get maximum output at maximum range.

Regulator IC 78C09 provides stable 9V supply to the oscillator, so variation in the supply voltage will not affect the frequency generated. You can also use a 12V battery to power the circuit. Assemble the circuit on a general purpose PCB. Install the antenna properly for maximum range.

Coils L1 through L5 are made with 20 SWG copper-enamelled wire wound over air-cores having 8mm diameter. They have 4, 6, 6, 5 and 7 turns of wire, respectively.

Source:Electronics For You Magazine http://www.electronicsforu.com/electronicsforu/lab/freecircuitslist.asp?id=464&title=Four-Stage FM Transmitter

Note: This transmitter is meant only for educational purposes. use of this transmitter with outdoor antenna is illegal in most parts of the world.

FM Transmitter circuit diagram

1 watt four stage fm transmitter circuit diagram


Reprinted Url Of This Article:
http://electroschematics.com/5594/four-stage-fm-transmitter/
Declaration
We aim to transmit more information by carrying articles .Please send us an E-mail to wanghuali@hqew.net within 15 days if we are involved in the problems of article content ,copyright or other problems. We will delete it soon .
Tags:
Previous:Circuit VOX simpluNext:1964 V8 Mustang and 6 Wiring Diagrams - Part 1
  • Hot Searches
TPA6011A4PWPRPrice:$1.35-$1.553-w Stereo Audio Power Amplifier With Advanced Dc Volume Control
TYN612Price:$0.42-$0.81SENSITIVE & STANDARD(12A SCRs)
2SK2615Price:$1.14-$2.28DC-DC Converter, Relay Drive and Motor Drive
TLV431BIDCKTPrice:$0.44-$1.26Voltage & Current References
CAT24C08WI-GT3Price:$0.11-$0.38EEPROM
24LC512-I/SMPrice:$1.32-$1.72EEPROM
SK12ADW01-003Price:$14.70-$19.70Keylock Switches
MC56F8323VFBEPrice:$7.11-$12.26Digital Signal Processors & Controllers - DSP, DSC
IKW25T120Price:$4.41-$8.82IGBTs - Single
STM32F103TBU6Price:$3.51-$3.97Microcontrollers - MCU