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Transmitter Circuits

Transmitters:  #'s       A - C       D - L       M - P       Q - S      
T - Z

Last Updated: November 22, 2021 03:00 PM

Circuits Designed by Dave Johnson, P.E. :
Inductive Pulse Receiver (175Khz) -  This circuit is discussed in more detail in the Experimenters Journal.  The receiverís six inch diameter coil detects the ring signal from the above transmitter and use a single NPN transistor to provided enough amplification for the signal to be easily viewed on an oscilloscope . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

Infrared Remote Extender Circuit -  This circuit is designed to be placed directly in front of a standard TV or VCR remote.  The exiting light pulses produced by the circuit match the pulses from the remote but are about 10 times more powerful . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000

Line-Powered Xenon Flash Transmitter -  This line powered xenon flash circuit drives a small camera type flash tube.  it has an optical isolator to allow the flash to be safely triggered from some remote device.  A flash rate of 2Hz is possible with the circuit. . . Circuit by David A. Johnson P.E.-June, 2000

Locate a Plastic Pipe -  I used this circuit once to track down the location of a plastic pipe, buried underground.  it transmits a weak RF signal, which can be picked up by a portable AM radio from about 6 feet away . . . Hobby Circuit designed by Dave Johnson P.E.-December, 2004

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-778-8407

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

FM Transmitter -  Here is the circuit diagram of the simple FM transmitter using a transistor.  Great performance or range is not guaranteed here, because this is an elementary design.  General purpose radio frequency transistor BF 494 (Q1) is used here for obtaining FM modulation.  A condenser mic is used here to pickup the sound. The condenser mic converts the sound to electrical variations and this variations are fed to the base of Q1 , which performs the amplification as well as modulation. The capacitor C2 and L1 determines the frequency of transmission. The circuit can be powered from a 9V transistor radio battery.__ 

FM Transmitter -  There is no thrill like the thrill you get from operating equipment you have built yourself.  if you have never built a project from a magazine before, let this be your first--you'll see how much satisfaction and fun you can have!  __ Designed by Tony van Roon  VA3AVR

FM Transmitter -  A portable FM transmitter that can be used to replace a FM microphone.   __ Designed by David Celestin

FM transmitter & PCB layout -  A simple 2 transistor circuit with a Coil on the PCB.   __ Designed by G.L. Chemelec

FM Transmitter (radiockt6) -  Colpitts oscillator.  its frequency depends on the capacitance of the vary cap diode.  The center frequency is changed by varying the biasing voltage of the vary cap through the 47K pot.  You can use a 75cm telescopic antenna or simply a length of hook-up wire.  Mine worked fine with a 6cm hook-up wire and gave a range of 100m with a good FM receiver.  The approx.  cost of the circuit is around Rs.35__ 

FM transmitter 0,4 W -  Schematic + Parts List + PCB __  Jan Kolar

FM transmitter 3 W (3W RF part) -  With good antenna (dipole placed outdoor and high) the transmitter has very good coverage range about 1500 meters, the maximal coverage range is up to 20 km __  Jan Kolar

FM Transmitter Bug -  The goal of this project is for me personally to learn a little more about fm transmitters and fm bug making (may the HAM radio gods bless me in this pursuit).  The ideal outcome of this project is a very small and full functional FM transmitter that we can stick into a plastic mint box.  in order to be able to build this, we'll have to learn a lot about amplifiers, LC oscillators, mixers, antennas and FM.  This project assumes you're already comfortable build your own PCB boards.  if you're not please take a look at the homemade pcb's tutorial before you continue.  it will help you out a lot.__ 

FM Transmitter for Band 2 VHF -  This small transmitter uses a Hartley type oscillator.  Normally the capacitor in the tank circuit would connect at the base of the transistor, but at VHF the base emitter capacitance of the transistor acts as a short circuit, so in effect, it still is.  The coil is four turns of 18swg wire wound around a quarter inch former.  The aerial tap is about one and a half turns from the supply end.  Audio sensitivity is very good when used with an ECM type microphone insert.   __ Designed by Andy Collison

FM transmitter for MP3 & MP4 Player, computer, Mobile Phone-high power transistor 2n2218 & 741 opamp -  Evolution FM transmitter with 2n2218 with audio amplification step using LM741 op amp with audio input for MP3, MP4, mobile, computer and other audio sources, beyond the traditional electret microphone.  With great sensitivity to the input signal.  Using fewer components and easy assembly makes it ideal for those who want even without much experience assembling __ Designed by Antonio Rodrigues

FM Transmitter using two transistors -  While there are a plethora of similar 2-transistor schematics available, this one is above average.  A major improvement over the little 1-transistor circuit that we've discussed previously, this transmitter consist of two stages.  The first transistor is used to amplify audio, which means that the microphone is now much more sensitive to sound.  The second one acts as an oscillator. __ Designed by Tomi Z

FM Transmitter with 2N2218 -  Here's simple FM transmitter circuit using medium power 2N2218 transistor.  Micropohone is of electret type that connects to two input terminals and the antenna should be a copper wire from 15 to 40 cm.  Below is schematic circuit of the fm transmitter.__ 

FM Transmitter with Crystal Referenced PLL Frequency Control using LMX1601 ATtiny2313, AT90S2313   -  An LMX1601 Phase locked loop, a discreetFET VCO, and an AVR micro controller combine to make a stable, easy to use monophonic FM transmitter that includes a an audio activated switch that turns the transmitter on only when its being used __ Designed by Dick Cappels

FM Transmitter with range of about 300 feet -  Here is the schematic, PC board pattern, and parts placement for a low powered FM transmitter.  The range of the transmitter when running at 9V is about 300 feet.  Running it from 12V increases the range to about 400 feet.  This transmitter should not be used as a room or telephone bug __ Designed by Aaron Cake

FM Transmitter with Varactor Diode Tuning -  Presented here is a low-power FM transmitter with varactor diode tuning using surface-mount devices (SMD) that will be received with a standard FM radio.  Soldering surface mounted devices is not so hard and actually is quite easy.  There are many designs for small FM transmitters but they have some problems.  First, you need an audio amplifier to get enough modulation.  Second, the antenna is attached directly to the collector.  Third, the coil L must be wound by hand adjusted by stretching.  it all ads with a weak signal that tends to drift in frequency.  in contrast the transmitter schematic we present here eliminates some of those problems, using varactor diode for tuning and modulation, givin great sensitivity without an audio amplifier.__ 

FM Transmitter-Miniature -  This miniature transmitter is easy to construct and it's transmissions can be picked up on any standard FM receiver.  it has a range of up to 1/4 of a mile or more.  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 diameter form __ Designed by Andy Wilson

FM Voice Transmitter -  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 (Tony van Roon's 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,  __ Designed by Tony van Roon  VA3AVR

FM Wireless Mike -  Low power frequency modulated transmitter using two transistors.  The circuit works with 9v power supply__ 

FM Wireless Mike -  Low power frequency modulated transmitter using two transistors.  The circuit works with 9v power supply__ 

FM/ AM Regenerative Receiver -  Two transistor receiver __ Contact blehack @ yahoo dot com

FM3 Mods -  Please remember, audio equipment can contain high voltages, so only undertake modifications if you know what you're doing.  Peter found that the following modifications gave improved performance from his FM3.  The capacitors that can be upgraded are C113 C114 and C121 in the PSU and C100 and C104 in the signal path.  They are clearly marked on the circuit board and have their polarity indicated with + and - symbols - you do need to fit the replacements the correct way round __ Designed by Peter Maddex

Four channel 433MHz remote control transmitter / receiver based on SM5162 & 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

Four channels RF wireless transmitter and receiver -  This is a very simple Wireless RF transmitter circuit that consists of the Holtek HT-12E encoder chip and AM 418MHZ-transmitter module (WZ-X01, other similar device can be used).  Using the hybrid RF xmit/receive modules make building the RF remote control a lot easy __ Contact info @ wzmicro.com

Four Transistor Tracking Transmitter -  Schematic and parts list only, no circuit description included.   __ Designed by Tony van Roon  VA3AVR

Four-Channel Remote Control -  You can construct your own long range infrared (iR) wireless remote using Motorola's MC145026 emitter and MC145027 detector chips.  With your remote you can control devices up to 20 feet (7 meters) away.  it operates similiarly to a TV remote.  You just point the emitter at the detector, push a transmit button.  The detector then interprets your data signal.  You can use this circuit to remotely turn on/off devices (like a motors, relays, home appliances).   __ Designed by Boondog web site

Four-Stage FM Transmitter -  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)...__ Electronics Projects for You

Four-Transistor Transmitter -  4 Transistor Transmitter - Circuit + Parts Lits + Notes __ Designed by Paul C. Sherby

Four-Watt AF Amplifer -  I have recently included a page about AF amplifers for use with Homebrew rigs.  in this I mentioned that I may include a practical one-watt circuit, complete with PCB foil and layout.  Here it is, but I have taken the liberty of engineering it to provide 4-watts of AF output and with a frequency response almost suitable for Hi-FI applications __ Designed by Harry Lythall-SM0VPO

Four-way remote control uses series transmission -  01/18/01 EDN Design ideas:  A simultaneous fourway 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.    Design by JM Terrade, Clermont-Ferrand, France

FOXBOX Transmitter Controller -  This FOX-BOX is based on a single CMOS 555 timer and uses an iSD1000 chip to store the transmit iD.   __ Contact Joe Leggio WB2HOL

Foxhole radio - true tinkering! -  Building a foxhole radio is rewarding and the basic setup is very simple. it is, however, difficult to adjust, and it may take several attempts to find a proper razor blade for the detector. This is a project that requires patience and much trial and error, but it will pay off once it begins to work. it will help to be versed in the construction and operation of crystal sets before building one. __  Brian Carusella

Frequency Agile 80m CW QRP Transmitter -  amateur radio construction projects.   __ Designed by Peter Parker

Frequency Dividers -  This paper is a collection of unusual frequency divider techniques which offer features not achieved with ordinary divider ICs  or prescalers __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Got Designs?
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if you want me to link to and/or post your original design Thanks.

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Transmitters:  #'s       A - C       D - L       M - P       Q - S       T - Z

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