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One Valve CW Transmitter - This one-valve (ECL82) CW Transmitter occupies a very special place in my amateur radio history. I was first licensed in 1994 but did not operate on air. I committed to only ever operate equipment which I had made myself. I had no time for radio construction and several years passed. in early 2002 __ Designed by Hans Summers
One Valve CW transmitter - This transmitter was first constructed in 1987 and provided the author with his first 'real' rig, capable of distances of more than about 100 metres. it performed better than expected, with 250km contacts being commonplace and 2500km being occasionally possible. __ Designed by Peter Parker
One Watt AM transmitter for the 10 meter band (28MHz) - in this project, you will make a simple 3-stage low-power broadcast-type circuit, using a crystal oscillator integrated circuit and an a collector modulated AM oscillator with amplifier. You can connect the circuit to the an electred microphone or amplified dynamic microphone. Using an electred microphone is shown (in gray) in the diagram below. (no amplified dynamic microphone has a to low output voltage to work. at least 100mv is needed). You could also add a LF preamp stage of one transistor to allow connecting a dynamic microphone directly. You'll see that you can receive the signal through the air with almost any AM radio receiver. Although the circuits used in radio stations for AM receiving are far more complicated, this nevertheless gives a basic idea of the concept behind a principle transmitter. Plus it is a lot of fun when you actually have it working! Remember that transmitting on the 10 meter band you'll need a valid radioamateur license! ! __ Designed by Guy Roels ON6MU
One Watt Class-C Amplifier - Schematic only, no circuit description __ Designed by © 2001 - YO5OFH, Csaba Gajdos
One Watt 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) and a power amplifier built around transistor 2N3866 (T4). A condenser microphone is connected at the input of the oscillator. __
One Watt RF Amplifier - This is a universal 1 Watt RF class C amplifier that is ideally suited for low power FM transmitters. input should be at least 100mW to achieve 1W output. it is recommended to enclose the amplifier in a metal case. __
One Watt RF Amplifier - This is a universal 1 Watt RF class C amplifier that is ideally suited for low power FM transmitters. input should be at least 100mW to achieve 1W output. it is recommended to enclose the amplifier in a metal case. __
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
Op Amp Radio - Here is a simple radio that is easy to build and inexpensive. in fact, you probobly have all the parts you need in your junk box. You'll be suprised at the great reception with this little set. __ Designed by Aaron Cake
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 µP when other components are asleep to receive and interpret any wake-up signal from the remote control or from the broadcasting company. These types Design by Christophe Basso, On Semiconductor, Toulouse, Cedex, France
PA Stage temperature controlled FAN speed controller - My Radio amateur callsign is OZ2CPU. I like to use Atmel AVR Atmega PIC 16 PIC 16F876 PIC 16F84. Most electronics easy made for the novice and something is for the more experienced. __ Designed by Thomas Scherrer OZ2CPU
PC or PICAXE interface for UHF remote control - Simple circuit lets you control the Oatley Electronics 4-Channel UHF Transmitter using a PC or PIC AX__ SiliconChip
Pen bugging Device ideal for corporate espionage - Our Pen Bug projects have been very popular. The idea of being able to hide a transmitter in a pen is very appealing. in an effort to reduce the size of this design, we have used surface-mount components. __ Contact Collin Mitchell
Pen FM Transmitter Bug - Pen FM Transmitter bug projects have been very popular. The idea of being able to hide a transmitter in a pen is very appealing. in an effort to reduce the size of this design, we have used surface-mount components. Firstly, the thought of using the coil in the tank circuit for transmitting RF was a little far fetched, but we used it as an example for those who were interested in experimenting with our circuits. Now we have gone back to a conventional antenna, the whip. The whip or straight-line antenna can be coiled, wound longitudinally or folded. The way it is wound makes a big difference to its effectiveness, but when you are limited in space, you have to accept these limitations. Even though we have used this antenna set up in our previous pen bugs we have considerably improved the circuit to the point were it has low battery consumption, but high RF output. The size of this design has been reduced considerably by using surface-mount components.__
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. __
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. __
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. __
Phone Tap - will record any conversation on any ph1-on same line, the circuit seems to be a bad design because it does not provide proper isolation and has too low DC impedance (can keep you line off-hook all the Time) __ Designed by Aaron Cake
Phone Transmitter - This small phone transmitter will transmit a phone conversation to an FM radio on the 88-108MHz band. it uses energy from the phone line to transmit the signal about 100 meters away. it uses the phone wire as the antenna and is activated when the phone is picked up. Transmitter components are mounted on a small PC board. PC layout is included.__
PIC16C505 IR/Wireless Remote Control - Control up to 8 devices by this easy constructable remote control. it can work as a radio or infrared remote control, depending on the components. Each device output can be configured to be momentary (turned on while you press the button) or latched. Latched outputs can be toggled on/off by one button per channel, or turned on and off by two buttons per channel. __ Designed by Peter Jakab
Pic-Plot GPIB to RS-232 converter - Get rid of dry plotter pens or unclear camera snapshots of test instruments when reporting your lab test session. This adaptor will capture plots or prints of your GPiB instrument to your PC through the serial port. __ Designed by Andrea IW9HJV and Johnny IW9ARO
Pic-Plot2 GPIB to USB converter - Pic-plot goes to USB Without any additional adapter, the new Pic-plot2 directly communicates with your PC or laptop through the USB port. Gives faster downloads from your GPiB instrument and it is self-powered from the host PC: no need of DC adaptor. __ Designed by Andrea IW9HJV and Johnny IW9ARO
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 __ Jan Kolar
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. . . Circuit by Dave Johnson P.E.-December, 2004
PLL Exciter - This is a PLL controller that works with the VCO/Modulator that I designed. Use these two modules together for a complete baseband-capable exciter unit. This PLL controller features a rock-stable crystal controlled reference, in conjunction with a programmable dividing network which allows the transmitter to be tuned in 100Khz steps from 79.9Mhz to 109.7Mhz by means of digital thumbwheel switches.__ Electronics DIY
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.__
PLL FM Transmitter - 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
PLL FM Transmitter using LMX1601, ATtiny2313 AT90S2313 - Here's a PLL FM Transmitter using LMX1601, ATtiny2313 or AT90S2313 microcontrollers. The common characteristic of all of the previous low power FM transmitters I'vebuilt over the decades, is that their operating frequency is determined by an LC resonant circuit. Some of them had excellent stability, some of them didn't, but I had always wanted to make one that is crystal controlled. Various schemes had been considered from time-to-time, including the direct approach of modulating the load capacitance of a a crystal oscillator, a whimsical phase modulation scheme involving a phase shifter, some balanced modulators, and limiting amplifiers, and at times, the down-to-earth and sober approach of modulating a VCO within a phase locked loop (PLL). While browsing Digikey's online catalog, I found the LMX1601 frequency synthesizer chip and thought: "Just maybe, the PLL approach is finally within my grasp." The LMX1601, which apparently was designed for use in cell phones, includes everything need to make two phase locked loops except for the VCOs. More importantly, one of the PLLs, specifically the "AUX" PLL, is specified to work in the FM broadcast band. The LMX1600 and the LMX1602 were also considered, but the LMX1601 was selected because it has a "500 MHz option", meaning that it can work down to about 50 MHz.__
PLL Stereo FM Transmitter - The circuit shown here is of a good Stereo FM transmitter that can transmit high quality signals up to a range of 70 feet. The circuit is based on BH1417 PLL stereo transmitter IC from Rhom semiconductors. The IC has separate audio processing sections for the left and right channels, pre emphasis circuit for improving signal to noise ratio, crystal control circuitry for accurate frequency locking, multiplex circuit for making sum (left plus right) and difference (left minus right) {see this article for better understanding Stereo decoder circuit} etc. Another important feature of this IC is that the transmission frequency can be set using a 4 channel DiP switch. The IC can be powered from anything between 4 to 6V DC and has an output power around 20mW. At full output power the circuit consumes only 20mA and has a channel separation of 40dB. There are 14 possible preset transmission frequencies, starting from 88.7MHz and incrementing in steps of 0.2MHz that can be selected using the DiP switch. The PLL circuitry of the IC is so precise that there is practically no frequency drift.__
PLL Synthesized FM Transmitter - The functioning of all is provided by a microcontroller from MIC ROCHiP "PIC 16F84" 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. __
Portable FM Transmitter - This portable FM Transmitter is easy to build. I have used a pair of BC548 transistors in this circuit. Although not strictly RF transistors, they still give good range. Transmitter is powered by 9V battery. The coil L1 consists of 7 turns on a quarter inch plastic former with a tuning slug. The tuning slug is adjusted to tune the transmitter. Actual range on my prototype tuned from 70MHz to around 120MHz. The aerial is a few inches of wire. Lengths of antenna wire should be 1 - 2 feet. The circuit is basically a radio frequency (RF) oscillator that operates around 70-120 MHz. Audio from audio jack is fed into the audio amplifier stage built around the first transistor. Output from the collector is fed into the base of the second transistor where it modulates the resonant frequency of the tank circuit by varying the junction capacitance of the transistor. Junction capacitance is a function of the potential difference applied to the base of the transistor. The tank circuit is connected in a Colpitts oscillator circuit.__
Portable FM transmitter 1 W - This small FM transmitter includes a limiter, a microphone amplifier and a PLL digital tuning. All the parts are placed on one circuit board. The RF power is switchable between 1W and 0, 2W __ Jan Kolar
Powerful AM Transmitter - The circuit for a powerful AM transmitter using ceramic resonator/filter of 3.587 MHz is presented here. Resonators/filters of other frequencies such as 5.5 MHz, 7 MHz and 10.7 MHz may also be used. Use of different frequency filters/resonators will involve corresponding variation in the value of inductor used in the tank circuit of oscillator connected at the collector of transistor T1.__
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. __
Protects Phone Line from Lightning Strikes - To build a circuit that will help protect your equipment from lightning strikes on the phone line. This circuit was actually designed to reduce or eliminate a very local broadcast AM radio stations signal from bombarding my parents telephone line, however it also turned out to be a really good lightning protector. __ Designed by Kevin Custer W3KKC
PSK Meter (updated 4'th of october 2005) - PSK-Meter is a controller board to prevent overload of a transmitted PSK-signal at the HF-bands (made in February 2004) __ Designed by Bjarke Korsgaard
PSK Transceiver, version 2 - Unique non-SSB transmitter design __ Designed by Steven "Melt Solder" Weber KD1JV
PTT and soundcard interface for the TM255/455 - Ham Radio - Modems and Soundcard interfaces __ Designed by Guy Roels ON6MU
PTT and/or soundcard interface - Ham Radio - Modems and Soundcard interfaces __ Designed by Guy Roels ON6MU
PTT Delay Circuit - The delay circuit is inserted between the controller and transmitter to provide a set-able time delay keeping the transmitter keyed when using "zero hang time" and linking to another machine. To use this circuit, the controller's repeater ptt must be configured "high true" (dip switch 2 on). __ Designed by Kevin Custer W3KKC
Puxing radio serial interface schematic, easy to make - Schematic only, no circuit description given __ Designed by Thomas Scherrer OZ2CPU
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