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

General Purpose RF Amplifier   -  The first article had a 3PDT switch that not only acted as a power switch, but also allowed the user to bypass the amplifier.  This would be very useful for areas with strong stations, to avoid overloading the receiver.  The second article utilized a ferrite bar antenna, which severely compromised sensitivity.  It did, however, include PCB artwork: __  Designed by Bruce Carter

Ham Radio BFO    -  circuit diagram of beat frequency oscillator using BF494 and how to listen amateur radio communication on ordinary BC receiver.   __

High Performance FM Receiver for Audio & Digital   -  These boards are designed to work together and include code to enable the digital audio connection __

High Power FM Microphone FM Bug   -  My FM Wireless Microphone has been a very popular project with beginners and experienced constructors alike.  It has been used inside guitars and as the basis of a remote control system.   __  Designed by Harry Lythall-SM0VPO

High Power FM Wireless Microphone   -  This FM Wireless Microphone has been a very popular project with beginners and experienced constructors alike.  It has been used inside guitars and as the basis of a remote control system.  I do however, receive many requests for a higher powered circuit and better microphone sensitivity.  This High Power FM Wireless Microphone has a better frequency stability, over 1 Km range and is good on microphone sensitivity.  This has been achieved by adding an RF amplifier buffer (with 10dB gain) and an AF preamplifier to boost the modulation a little. __

High quality AM through your FM stereo   -  amateur radio construction projects.   __  Designed by Peter Parker

Homemade Variable Tuning Capacitor   -  A 'Multi-Turn' Homemade Variable Tuning CapacitorA remarkably simple Homebrew device for tuning in your FM stations! __  Designed by braincambre500 @ yahoo.com

How to Build a 300MHz AM RF Remote Control System   -  If you plan to build this project, simply replace the RE-99 receiver & TX-99 transmitter with the RWS-434 & TWS-434A RF receiver & transmitter modules found HERE.  These circuits will work with any RF transmitter and receiver modules.  Due to the huge interest in this project, I have just recently finished the NEW schematics.  The older schematics were scanned and pretty poor quality.  These new ones should make it considerably easier to recognize the parts used for the project.   __  Designed by Reynolds Electronics

Improved AM Micropower Transmitter   -  The following circuit is an improved version of the transmitter above.  It features a high Q pot core autotransformer that provides a very high voltage to the antenna, greatly improving the range and an improved crystal oscillator section.  (Also see phono oscillator for a tunable version.) __   Contact Charles Wenzel of Wenzel Associates, Inc.

Improved 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

Improved frequency Modulator uses negatron   -  07/11/02 EDN-Design Ideas - You can improve a capacitive-sensor circuit with a modulator and an RF transmitter(Reference 1] by modifying the modulator portion to obtain better accuracyimprovements result from adding a "negatron" circuit, a configuration that uses equivalent negative capacitance.  Reference 2 gives some insight into the uses of negative impedance - Circuit Design  by  Alexander Bell, Infosoft International, Rego Park, NY

Inductance/Capacitance Meter Project   -  I have taken these two projects from the ARRL Handbook 2002.  It had been in the book for a few years now.  A couple of years ago I made both of the projects, and they have been performing well since.  Since the words and schematics were so small and unclear, I had decided to re-type all the text and re-do both schematics.  as to make it easier for viewing.   __  Designed by braincambre500 @ yahoo.com

Inductively sense aircraft engine valve position   -  04/25/14 EDN-Design Ideas - Aircraft engine designers are conservative by nature, but here's a way to improve performance anyway.  This design uses an inductor to sense the position of a valve on an aircraft engine as a way to get camshaft position information.  Knowing the camshaft position along with the crankshaft position allows fuel injection while the intake valve is open and the use of individual coils for each cylinder.   - Circuit Design     by  Angus McCamant

Jitter Modulator   -  Schematic Only __   Contact info @ forsselltech . com

KD2BD ATV AM Video Modulator   -  video signal processing circuit that allows adjustment of video gain, video bias, sync and sync level __

LA1800 FM Radio   -  3V superheterodyne FM receiver __  Contact hp6y-isym @ asahi-net.or.jp

LF LowFER Beacon Transmitter   -  Here's a complete LF Beacon transmitter for LowFER   (Low-Frequency Experimental Radio).  The transmitter is designed for license-free operation between 160 kHz and 190 kHz, consuming the legal limit of 1 watt power input to the final RF output stage.  For fun, the complete transmitter is built into an Altoids mint tin.  The circuit is built dead-bug style on a piece of copper clad circuit borad material, lightly painted with Testors transparent Hot Rod Red to prevent tarnish.  The paint doesn't seem to make soldering any more difficult.  The board is grounded to the tin in a few places.   __   Contact Charles Wenzel of Wenzel Associates, Inc.

Limiting Amplifier Forms AM Modulator   -  12/07/95 EDN-Design Ideas - he wIdeast use of limiting amplifiers is for clamping analog signals within a desired range.  However, limiting amplifiers with fast overdrive-recovery times and wide bandwidth have an interesting additional application: You can use these amplifiers to form AM modulators.  Typically, you provide dc voltages for the high and low clamp levels, and the amplifier limits its output range to those levels, regardless of the input overdrive.  Properly designed limiting amplifiers have a fast overdrive-recovery time, which allows them to quickly return to linear operation when the input falls within the clamp levels.   - Circuit Design  by  Ronald Mancini and Mark Amarandos, Harris Semiconductor Melbourne, FL, and Costa Mesa, CA-- 12/07/95

Linear FM 30Watt    -  A amplifier of medium force RF for the FM, is always essential for the amateur that wants it strengthens some small transmitter, that likely it has already it manufactured! The present circuit can give force 25-30W, with control no bigger than 4-5 W. __  Contact IQ Technologies

Linear FM 50Watt with BLY90   -  A amplifier of force RF for the FM, is always essential for the amateur that wants it strengthens some small transmitter, that likely already it has manufactured or has been supplied ready.  The present circuit can give 50-60W RF force of expense, with control smaller than 15-20W in the region of frequencies of FM, that is to say in the 88-108MHZ.  Transistor that we selected for __  Contact IQ Technologies

Little Jim AM Transmitter   -  A Flea-Power Unit For The AM Broadcast Band___ SiliconChip

LONG RANGE FM TRANSMITTER   -  Several circuits for constructing FM transmitters have been published in EFY. The power output of most of these circuits were very low because no power amplifier stages were incorporated. The transmitter circuit___ 01/01/2007 - EFY

Long-Range FM Transmitter   -  Several circuits for constructing FM transmitters have been published in EFY.  The power output of most of these circuits were very low because no power amplifier stages were incorporated.  The transmitter circuit___ Electronics Projects for You

Low Pass Filter for FM 88-108 MHz   -  Filter used for eliminate unwanted harmonic frequency at second and third.  Notch filter, Band Pass Filter (BPF) , and High Pass Filter (HPF) sometime combined in constructing LPF design.  Schematic below for FM Broadcast Lowpass Filter 88-108 MHz __

Low Power FM Transmitter   -  Useful to retransmit the hi-fI to another FM receiver nearby, or as a wireless mic __  Designed by Rod Elliott  ESP

LowPass Filter   -  The schematic you find here comes from another site on the internet, but because it's on so many sites, we don't know who actually designed it.  However it's a nice one.  Capacitors: C1, C4 22pF cer.  C2, C3 51pF cer.  Coils: L1, L2, L3 #18 bus wire, 1/4"diameter, 3 turns * Form the leads from the capacitors as shown in the little figure below.  Then solder them from the pad to the outside ground area.  * Be sure that the turns from the coil are seperated by the same distance as the diameter of the wire * Form the leads from the coils as shown in the little figure below.  Then solder them in place.  * Place the filter in a metal box, with rf-connectors on both ends ( SO239 (=PL259) , BNC or N-connectors)  __

Low-Range AM Radio Transmitter   -  Here is a simple radio transmitter for transmission up to 25 metres.  It is basically an AM modulator whose signal can be received on the normal AM radio.  It can also___ Electronics Projects for You

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

 


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