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Modulator Circuits
Modulators:  #'s - A        B - F        G - M        N - T        U - Z
 

Last Updated: October 24, 2017 02:55 PM

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Feedback FM Receiver   -  Based on Valvo FD-1A module, TBA120, and MC1310 All other components discrete and mounted on a single PCB Originally published in Elektuur magazine (nov 1974) __  Designed by Aren van Waarde

Field Strength Meter for the FM Transmitters   -  This fun project is a home-made 'Tunable Field Strength Meter', tunable for FM Transmitters operating in the FM Broadcast Band.  Below is the detailed plans on how to make this project a success! The layout of the circuitry is small enough for the finished unit to be placed directly on top of your DVM, in order to keep output leads of the FSM as short as possible.  I had made mine on a 2 inch by 2 inch piece of PCB.  which is MORE then enough room to place the entire circuitry on.   __  Designed by braincambre500 @ yahoo.com

FM Band Monaural Transmitter   -  A high quality monaura FM transmitter is quite useful in a variety of applications.  The audio from a TV or entertainment system may be transmitted for remote or portable listening and for wireless earphone listening.  The audio from an AM receiver placed near a window can be retransmitted within a metal building where AM reception is not possible.  Two transmitters will convert two portable __   Contact Charles Wenzel of Wenzel Associates, Inc.

FM Band Preamplifier   -  Here is a high performance RF amplifier for the FM band which can be successfully built without any special test equipment.  The grounded-gate configuration is inherently stable without any neutralization if reasonably good layout techniques are employed.  The output transformer is designed to resonate with the FET's drain capacitance at about 92 MHz giving the amplifier the highest gain at the low end of the band where the weaker stations operate.  No tuning capacitor is needed as long as the transformer is built precisely as described  __   Contact Charles Wenzel of Wenzel Associates, Inc.

FM Beacon Transmitter (88-108 MHz)   -  This circuit will transmit a continuous audio tone on the FM broadcast band (88-108 MHz) which could used for remote control or security purposes.  Circuit draws about30 mA from a 6-9 volt battery and can be received to about100 yards.   __  Designed by Bill Bowden

FM Booster   -  Here is a low-cost circuit of an FM booster that can be used to listen to programmes from distant FM stations clearly.  The circuit comprises a common-emitter tuned RF preamplifier wired___ Electronics Projects for You

FM Broadcast Audio Transmitter   -  A nice AC mains powered transmitter with pre-emphasis, audio level control, and tuning control.  Notice: Before operating a radio transmitter, find out what kind of transmitter operation, if any, is permitted in your locality.  Radio transmitter operation is a serious legal matter.  In the United States, operation of unlicensed intentional radiators is covered by Part 15 of Title 47 of the Code of Federal Regulations.  This design can be readily adapted to different frequencies and different power levels.  If you choose to build and operate the transmitter described here, you do so at your own risk.   I'm only publishing this as an example of what can be done.   __  Designed by Dick Cappels

FM Bug   -  This FM bug transmitter circuit will let you spy on people.  The transmitter can be placed in the desired room and the conversation heard from a place far away just using___ Electronics Projects for You

FM bug 420-480 MHz   -  How about getting that old Nokia phone out of your drawer and turning it into something freakishly cool? I will not lie to you, you will need a few tools and skills such as soldering/desoldering and making PCBs.  Here you can download Sprint-Layout __

FM Bug-transmitter   -  The circuit consists of two separate stages.  The first is an audio pre-amplifier and the second is a 90MHz oscillator.  The first stage is very simple to explain.  It is a self-biasing common-emitter amplifier capable of amplifying minute signals picked up by the electret microphone __  Contact kit is designed and manufactured TALKING ELECTRONICS

FM Microphone   -  Here is the super NEW miracle improved "Frequency Modulation Wireless Microphone" (BUG) with added easablilty, readability and copyability.  This was necessitated after the number of E-Mail questions posed by people who were confused by the layout of the project (s).  Before proceeding with the interesting bits, please note __  Designed by Harry Lythall-SM0VPO

FM Microphone   -  A micro-transmitter is so small and sensitive, it have only 8 easy-to-get parts and can be assembled in one hour.   __  Designed by Jose Pino

FM Radio Microphone with Internal Loop Antenna   -  This article began as a design guide for hyper cranial erogenic field generators, however, your primitive earth brains are completely unable to respond to erogenic fields in the 100MHz region.  I personally had a brain upgrade (for purely medical purposes of course) so I am able to respond __   Contact Charles Wenzel of Wenzel Associates, Inc.

FM Radio Receiver   -  Frequency adjustment is accomplished with BB105 varicap diode __

FM Radio Transmitter   -  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 David Sayles

FM Radio Transmitters with Opamp   -  An low power FM Transmitter using an op-amp as the audio preamp and a single transistor as the RF amplifier.   __  Designed by Kamran Ahmed

FM Receiver using MPF102   -  An FM regenerative receiver using a single FET and one audio amplifier IC.   __  Designed by Andy Collison

FM Receivers   -  Here is how you make a superregenerative circuit.  Choose a regenerative amplifier circuit configuration that requires more current during oscillations than when not oscillating.  Adjust the regenerative amplifier to oscillate.  Add a small circuit that uses the current of the amplifier to charge a capacitor while oscillations are taking place.  Once the capacitor is charged, the voltage on __

FM Stereo Modulator   -  This circuitry is used for generating a high quality FM stereo multiplex signal that is suitable for driving mono FM transmitters.  The Rev E2 FM stereo multiplex generator is the most recent design in a series of circuits that have appeared on this site.  This version features improvements to the audio mixer stage, better gain adjustments in the audio filter stage and a rework of the multiplexer stage.  When it is adjusted properly, the Rev E2 design produces an FM stereo signal with excellent fidelity. __  Designed by Forrest Cook

FM Synthesizer N1   -  In order to simplify the transmitter design, we've used the new pll circuit from Motorola :the MC145170.  This PLL includes the prescaler and a serial standard bus called SPI.   __  Designed by Michel P

FM Synthesizer N2   -  This new FM transmitter is very simple and doesn't need any RF tuning.  First of all , we have used an integrated VCO: The POS150 from Mini-circuits.  This excellent RF circuit covers all the FM Band in a voltage range of 4V to 8V.  The Kvco factor is very stable all over the FM band, (08/08/08)  __  Designed by Michel P

FM Telephone Bug   -  Receive telephone conversations on any FM radio with this neat little device.   __  Designed by Tony van Roon  VA3AVR

FM Telephone line Bug Transmitter   -  Here is a simple transmitter that when connected to a phone line, will transmit anything on that line (execpt the dial tone) to any FM radio.  The frequency can be tuned from 88 to about 94Mhz and the range is about 200 feet.  It is extremely easy to build and is therefore a good, useful beginner project.   __  Designed by Aaron Cake

FM Telephone Transmitter   -  Receive telephone conversations on any FM radio with this neat little device.   __  Designed by Tony van Roon  VA3AVR

FM Transmitter   -  While there are a plethora of similar 2-transistor schematics available, this one is above average.  A major improvement overlittle 1-transistor circuit that we've discussed previously, this transmitter consist of two stages.  first transistor is used to amplify audio,  __

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 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 Circuit   -  Schematic only, no circuit description is included __  Designed by Kamran Ahmed-UK

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 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 and 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/ 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

Forced quenching improves three-transistor FM tuner   -  EDN-Design Ideas - 02/29/2016    That an FM tuner can be built using one transistor is impressive.  This Design Idea is the luxury three-transistor version of that! - Circuit Design  by Lyle Williams

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

Frequency Calibrator for AM & Shortwave Radios   -  Antique transistor and tube AM/short wave radios can be fun restoration projects.  One of the restoration tasks involves the alignment of the receiver's local oscillator so that the dial readout correctly represents where the receiver is tuned.  This circuit can produce AM-modulated tones on various frequencies that these receivers pick up.  The circuit can produce signals at 10, 5, 2.5, 1.25 and 0.6125 Mhz.  By changing the master oscillator block from 10 Mhz to 16Mhz, the generated frequencies can be changed __  Designed by G. Forrest Cook

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Modulators:  #'s - A        B - F        G - M        N - T        U - Z

 


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