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Transmitter Circuits
Transmitters:  #'s       A-C       D-G       H-Q       R-T      
U-Z

Last Updated on:
Sunday, August 23, 2015 06:02 AM


Circuits Designed by Dave Johnson, P.E. :
  • 3Khz Filter + Audio Amplifier -  This circuit is the audio amp section for a complete optical transmitter. The circuit amplifies and filters the voice audio signals from an electret microphone. The circuit is described in more detail in . . . [Hobby Circuit designed by David A. Johnson P.E.,  06/04/00]
Circuits Designed by Dave Johnson, P.E. :

3 Channel IR Remote Control -  This project is a 3-channel IR remote control with 3 output relay and easy to build. Features: CPU PIC12F629 at 4MHz crystal for Tx/Rx, 3 channel output relay, The Tx use sleep mode for saving battery power, Use Phillips RC5 protocol, distance more than 7 m, Easy circuit to build and assembly and small amount of components. Uses RC5 protocol which is probably the most used by hobbyists, probably because the wide availability of cheap remote controls and easy to understand. . . .  [Unfortunately designer's name is not given]

3 Channel RF Remote Control -  This is a 3 channel RF remote control project. The transmitter powered by 3V battery (coin size) range about 10 m. This remote control I use PIC12F509 from Microchip which is a 8-pin single-chip microcontroller designed for low pin count applications with 1 K words flash memory and 41Byte SRAM and some special features such Power-saving Sleep mode, Wake-up from Sleep on pin change. . . .  [Unfortunately designer's name is not given]

3 Watt FM Transmitter -  This is the schematic for an FM transmitter with 3 to 3.5 W output power that can be used between 90 and 110 MHz. Although the stability isn't so bad, a PLL can be used on this circuit. This is a circuit that I've build a few years ago for a friend, who used it in combination with the BLY88 amplifier to obtain 20 W output power. From the notes that I made at the original schematic, it worked fine with a SWR of 1 : 1. 05 (quite normal at my place with my antenna). . . .  [by Aaron Cake]

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

30 Meter QRP Transmitter for Morse Code -  This transmitters' intended purpose is for morse-code only in30 meter band (Tony van Roon's 10Mhz). It is a low-power QRP type and needs to be connected to your existing tranceiver. harmonic rejections onprototype were measured at 40dB on 20Mhz and 50dB on 30Mhz. . .  [Tony van Roon's circuit]

300 MHz Prescaler -  A preamp that drives the CMOS counter input and a divide by 10 prescaler to extend the range of A Little More Serious Frequency Meter. The MCT10280 prescaler can be set to divide by 80, 40, 20, or 10, as a function of which pins are tied to the power supply. I set this one to divide by 10 since it is adequate for my needs, and the mental calculation of multiplying the meter reading by 10 is not taxing. One problem with the MCT10280 is that if it doesn't have an adequate input, the output is very noisy, which shows up as counts in the couple MHz range on the frequency meter. This noise shows up if the signal amplitude the signal frequency is too low. For this reason, I only intend to use the prescaler with inputs between 10 MHz and 300 MHz. . .  [Designer's name not included]

303MHz TRANSMITTER with 32kHz Crystal -  We have covered 27MHz (and 49MHz) links on P1 and P2 of this article and shown how to produce a simple circuit (or buy a toy for less than $10. 00) and get 4 or 5 channels.
We also showed how to produce on/off from a single channel and how to detect 27MHz with a Field Strength Meter. . .  [Collin Mitchell's web site]

30W VHF FM Amplifier for 88-108 MHz with BLF245 MOSFET -  The achievement of this 30-watt amplifier has been designed to take place on a heatsink microprocessor PC equipped with its fans, the advantage of this method of cooling has been selected for the fact that (French . . . 

350W QRO with GK71 for 160-15m -  Schematic only, no circuit description. . .  [© 2001 - YO5OFH, Csaba Gajdos]

3Khz Filter + Audio Amplifier -  This circuit is the audio amp section for a complete optical transmitter. The circuit amplifies and filters the voice audio signals from an electret microphone. The circuit is described in more detail in . . . [Hobby Circuit designed by David A. Johnson P.E.,  06/04/00]

3m 100 MHz small bug -  . . . 

3V FM Transmitter for 88MHz to 108MHz -  The important part of the circuit is formed of the Colpitts type oscillator. C3, C4, C5, C6, CD1-CD2 and L1 determines the frequency. BF982 and dual gate MOSFET are active parts in oscillator. When the input impedance of the MOSFET gate inputs are high, LC tank is not affected. However transistors force the LC tank and cause phase shift. Two driver stages are added to isolate the antenna from oscillator. First stage (BF199) amplifies the low signal of the oscillator and works as a constant load. The second stage (BFR90) amplifies the signal going through the antenna some more. . . . 

3W FM Transmitter -  This is the schematic for an FM transmitter with 3 to 3.5 W output power that can be used between 90 and 110 MHz. Although the stability isn't so bad, a PLL can be used on this circuit. This is a circuit that I've build a few years ago for a friend, who used it in combination with the BLY88 amplifier to obtain 20 W output power. From the notes that I made at the original schematic, it worked fine with a SWR of 1 : 1. 05 (quite normal at my place with my antenna). . . .  [Circuit designed by Aaron Cake]

4 channel 433MHz remote control transmitter / receiver based on SM5162 and SM5172 chips -  The radio control uses pre-calibrated 433 MHz transmitter and receiver modules. The SM 5162 presents a code to the transmitter module depending on the status of the input switches. The 555 is configured to provide a regular pulse to the 'transmit enable' (pin 15) of the SM 5162 - this pulse runs at a frequency of about 7 Hz (the LED will flash with each transmission). This means that the transmitter will update the code transmitted 7 times a second. . . .  [CdS Electronic's website]

4 Transistor Transmitter -  This circuit provides an FM modulated signal with an output power of around 500mW. The input Mic preamp is built around a couple of 2N3904 transistors, audio gain limited by the 5k preset. The oscillator is a colpitts stage, frequency of oscillation governed by the tank circuit made from two 5pF capacitors and the inductor. . .  [Design by Paul K Sher[by]

40 Meter, 5 Watt QRP Transmitter -  As ham operators, we like to broaden our horizons by trying something new. There is nothing more satisfying about this hobby than building your own transmitter. The circuit in figure 1 is a crystal controlled CW transmitter with at least 5 watts of power. (The prototype generated 7 ˝ watts) This circuit was built on a Radio Shack universal board (276-168B) and worked extremely well the first time. . .  [Radio Amateur Society of Norwich]

40 Watt Amplifier for FM Broadcast -  This amplifier was built based on Marconi's website, A Design for a 40W broadband VHF RF Power Amplifier for FM broadcast. A few minor tweaks were made to the schematic and a few parts were changed to what I had available (mostly surface mount components). The heatsink is from an old Motorola Mostar 800 MHz radio, and has the perfect heatsink island to match the MRF171A. . .  [designer's name not found on the website]

400mW VCO FM transmitter -  With good antenna (dipole placed outdoor and high) the transmitter has very good coverage range about 500 meters, the maximal coverage range is up to 4 km. . . . 

40W broadband VHF RF Power Amplifier for FM broadcast -  To boost the output power of low power FM broadcast band exciters, a number of these are available commercially, both as kits and ready made. . . . 

4-20 mA Digital-to-Process Current Transmitter -  AN-21 Analog Devices App Note - Describes a 3 I. C. Digital to 4-20 mA Current Output Circuit (DAC08, REF01 and OP221) . . . 

432 MHz kilowatt Amplifier -  Schematic only, no circuit description. . .  [by W1QWS]

434MHz short-range communications -  article from Elektor 1998/5. . . .  [Peter Jakab, Electrical Engineer, Engineer of Informatics]

434MHz transmitter using SAW resonator -  Scroll to find this circuit. . .  [Peter Jakab, Electrical Engineer, Engineer of Informatics]

4-Transistor Transmitter -  This circuit provides an FM modulated signal with an output power of around 500mW.   The input microphone pre-amp is built around a couple of 2N3904 transistors (Q1/Q2) , and audio gain is limited by the 5k preset trim potentiometer. The oscillator is a Colpitts stage, frequency of oscillation governed by the tank circuit made from two 5pF ceramic capacitors and the L2 inductor. . .  [Paul C. Sherby's circuit]

4W FM Transmitter -  As it has already been mentioned the transmitted signal is Frequency Modulated (FM) which means that the carrier’s amplitude stays constant and its frequency varies according to the amplitude variations of the audio signal. When the input signal’s amplitude increases (i. e. during the positive half cycles) the frequency of the carrier increases too. . .  [Designer's name not included]

4W 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. . .  [by IQ Technologies Industry, unless otherwise noted online]

4-way remote control uses series transmission -  01/18/01  EDN Design Idea   A simultaneous four way remote-control system adheres to size, cost, and reduced-complexity constraints and uses a series transmission to drive parallel loads (Figure 1). You can use.  PDF has several circuits, scroll down. . .  [by JM Terrade, Clermont-Ferrand, France]

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Transmitter Circuits
Transmitters:  #'s       A-C       D-G       H-Q       R-T      
U-Z


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