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Transmitter Circuits, Page 4
Transmitters:  #'s - B       C - F       G - M      N - S      T - Z
Last Updated on: Wednesday, July 16, 2014 06:35 AM

Circuits Designed by Dave Johnson, P.E. :
  • Plastic Pipe Finder
    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.

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

One Valve 3.5MH CW Transmitter -  amateur radio construction projects…. [from Peter Parker's website]
One Valve CW transmitter -  amateur radio construction projects…. [from Peter Parker's website]
Op Amp Based FM Transmitter -  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]
Open-loop power supply delivers as much as 1W 01/18/01 EDN-Design Ideas....For VCRs, TVs, and other equipment that requires a standby mode, you must supply power to a mP when other components are asleep to receive and interpret any wake-up signal from the remote control….PDF has several circuits, scroll down…. [Design Idea by Christophe Basso, On Semiconductor, Toulouse, Cedex, France]
Optical Module Development Platform 2.5 GBPS Transmitter with Digital Diagnostics -  AN-654 Analog Devices Application Notes....[App Note]
Pen bugging device ideal for corporate espionage -  (diagram added 05/07)
Phone FM Transmitter -  This Phone FM transmitter connects in series to your telephone line and transmits the telephone conversation over the FM band when you pick up the telephone handset. Transmitted signal can be tuned by any FM receiver. The circuit includes an "On Air" LED indicator and also provides a switch which can be used to turn off the transmitter. A unique feature of the circuit is that no battery is needed to operate the circuit since power is taken from the telephone line.

PIC16C505 IR/Wireless Remote Control -  .... [Peter Jakab, Electrical Engineer, Engineer of Informatics]
Pira CZ 5W PLL FM Transmitter -  Easy to build high-quality PLL FM transmitter with typical output power of 5 W and no-tune design…....
Plastic Pipe Finder -  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. …. [Designed by David A. Johnson]
PLL FM Transmitter -  This is PLL FM Transmitter using SAA1057 chip. Transmitter can be operated from a PC through LPT port, or using a PC software as a driver.
Powerful AM Transmitter -  ....
Prescaler with Counter -  Digital frequency counter is being used for wide range of applications. Digital frequency counter extensively uses digital circuits and hence fairly good knowledge of digital circuits and of digital integrated circuits is required to understand the operation of the frequency counter. However a person who is not familiar with any electronics circuits and experiments has in written this article.
QRP HF Transmitter -  Electroinic circuit design…. [from Harry Lythall's website]
QRP Keyer -  very simple keyer circuit using only one transistor......
QRP SSB Transmitter -  Electroinic circuit schematic…. [from Harry Lythall's website]
Quality FM Transmitter -  ....
Radio Remote Control using DTMF -  Here is a circuit of a remote control unit which makes use of the radio frequency signals to control various electrical appliances.  This remote control unit has 4 channels which can be easily extended to 12.  This circuit differs from similar circuits in view of its simplicity and a totally different concept of generating the control signals.... [Radioland.net]
Radio Shack Special-Transmitters (Patrick Cambre) -  (electronic schematic / circuit added 08/09)
Ramsey 25 BA1404 Stereo FM Transmitter -  Stereo FM transmitter based on BA1404 and 145170 frequency synthesizer IC.
Remote control using VHF modules -  A few designs for remote control switches, using VG40T and VG40R remote control pair, are shown here. The miniature transmitter module shown in Fig. 1, which just measures 34 mm x 29 mm x 10 mm, can be used to operate all remote control receiver-cum-switch combinations described in this project.... [Radioland.net]
Remote RF Xmiter -  This device was built into a small (1 1/4 by 2 inch) Radio Shack project box. It features four push buttons which can produce 2 codes each. (Pushing a button for less than one second sends the first code, holding it for over one second sends the second code.) [Luhan Monat - Mesa Arizona]
RF Amplifier 25W  -  FM 88-108MHz RF amplifier 25W  ....
RF Buffer Stage -  This bufferstage is intended to be used after a BF900 or BF199 (even a BF245) oscillator. It delivers several milliwatts and is perfect to drive a 2N2219 or 2N4427. Be sure the coils are really round and can "see" each other: place metalplates between the coils. The supply voltage is around 12V (typ. 13,8V).
RF Power Meter -  RF Power Meter for QRPers
RF Power Meter -  RF Power Meter for QRPers  (electronic circuit added 03/04/05)
RF Preamplifier -  Input needs only several mWatts (e.g. BF900) -> 300 mWatts OUT.  This schematic is a often used buffer. It's easy to build, clean and cheap. When you want even more power, you can replace the 2N2219a by a 2N4427 or 2N3553. You can lower the output by adding a little resistor (10..47 Ohm 1/2W) in the emitter line of the 2N2219a.
RF Transmitter -  (electronic circuit added 7/03)
RF Transmitter for PIR Sensors -  (electronic diagram added 6/03)
RF Transmitter Light Sensing -  Photo sensor is placed in series with a resistor…. [Tony van Roon's circuit]
RF Transmitter uses AMI encoding -  11/24/99 EDN-Design Ideas....Although alternate-mark-inversion (AMI]encoding is well-suited for direct-conversion FM transmission, designers often overlook the technique. AMI, a three-phase, synchronous-encoding technique, uses bipolar pulses to represent logic ones and no signal to.... EDN is migrating links. This link is not verified.  Search the "title" + "EDN" for new link.
RF/SS Handie Hopper Transmitter Schematic -  (electronic circuit added 7/03)
RFPIC12F675 Transmitter Module -  Microchip Application Note Published 20-Jun-03  (app note added 2/06)
RF-telemetry transmitter features minimal parts count -  6-Jan-05 Issue of EDN  Requirements for portable, short-range telemetry systems frequently include low power consumption, small size, and low cost. The circuit in Figure 1 meets these criteria and uses only three off-the-shelf ICs and a few passive components. Although dedicated to conditioning the low-level signal a strain-gauge bridge produces, the circuit can operate with almost any resistive transducer based on.... [Design Idea by Francis Rodes, Eliane Garnier, and Olivier Chevalerias, ENSEIRB Talence, France]
SAA1057 PLL Synthesized FM Transmitter -  The functioning of all is provided by a microcontroller from MICROCHIP "PIC16F84" which provides support for buttons, LCD 2 lines of 16 characters and the circuit pll "SAA1057. The VCO is entrusted to the transistor Q8 associate of his two diodes varicaps "BB109, a floor buffer Q7 separates the VHF signal obtained in two ways, on the one hand to Q9 to enslave loop phase and on the other hand to the Q5 and Q6 together which takes care to amplify the signal before attacking Q11, a "BFR96" which plays the role of HF switch via a timer "NE555" which receives information from the push and "SAA1057" ensuring HF cutoff in the event of failure of a locking or unlocking of the pll.
Sensitive FM Transmitter -  ....
Shortwave Bug -  Circuit and notes only, no circuit description given…. [Tony van Roon's circuit]
Short-wave Radio -  Schematic only, no circuit description
Short-wave scanner converter -  Schematic only, no circuit description
Shortwave Transmitter -  ....
Simple FM Microphone -  Electroinic circuit schematic…. [from Harry Lythall's website]
Simple FM Transmitter Schematic -  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!… [Tony van Roon]
Simple RF Power Meter -  Here is a simple set up which will enable them to measure the out put power of their transmitter. All that they require is a good multimeter which has a sensitivety of 20k ohms/4 Watts which is adequate for low power transmitters.  ....
Simple RF Transmitter -  (electronic circuit added 7/03)
Simple speakerphone -  (electronic design added 6/07)
Simplest RF Transmitter -  A very simple radio transmitter…. [Tony van Roon's circuit]
Single Channel RC Cars TX & RX  -  Here is the 9 volt GS transmitter which does not use a crystal.  This clever design allows only two transistors to generate both the carrier and  the modulation. Shown below at 27MHz 40MHz and 49MHz: (added 2/05) [Reverse engineered schematic by Stepan Novotill]
Single Chip FM Transmitter  -  Simple to build once chip FM Transmitter that requires only 3, 5V to operate.  This transmitter links your home-entertainment system to a portable radio that can be carried around the house and into the back yard. For example, you can play music on the CD....(added 8/08)
Small bug using SMT surface mount technology -  (schematic / circuit added 05/07)
Small circuit forms programmable 4  to 20 mA transmitter -  17-Apr-03 Issue of EDN  One of the key challenges in the design of 4- to 20-mA current transmitters is the voltage-to-current conversion stage. Conventional transmitters use multiple op amps and transistors to perform the conversion function. These approaches have been around for a long time, but they are usually inflexible, have poor power efficiency, and have limited current compliance.... [Design Idea by Alan Li and Jeritt Kent, Analog Devices, Bellevue, WA]
Small FM transmitter SMD -  (electronic design added 6/07)
Small Radio Transmitter -  (electronic circuit added 7/03)
Solar Powered FM Bug -  There are many miniature FM transmitter (bug) circuits online, this one is unique in that it runs completely on solar power. No battery is required. As long as the sun is shining on the PV panel, the circuit will transmit. The bug is useful as a "remote ear", and can be used for anything from listening birds to surveillance work. The mic preamp and oscillator circuits were borrowed from a common circuit found around the Internet, I added a regulated solar power supply and an RF amp that extends the range and improves frequency stability.... [G. Forrest Cook]
Spark gap Transmitter -  The first thing I want to stress is that "SAFETY WAS NOT A MAJOR CONCERN" during the days of Spark, some of the methods used were VERY DANGEROUS. Now that I have said that, let me move on. There was a certain amount of excitement that was assoicated with Spark Gap transmitters. Without getting into the theory or design of these Spark Gap Wireless transmitters, let me attempt to give you an over-view of their operaton.... [Designed by w1fji]
Spark-gap transmitter -  (circuit added 6/07)
Stereo FM Transmitter -  AN-543-StereoFMTransmitter-Analog Device Application Notes....[App Note]  
Surveillance Transmitter Detector -  This circuit can be used to "sweep" an area or room and will indicate if a surveillance device is operative. The problem in making a suitable a detector is to get its sensitivity just right, Too much sensitivity and it will respond to radio broadcasts, too little, and nothing will be heard. [Andy Collison]

Transmitters:  #'s - B       C - F       G - M      N - S      T - Z

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