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Electronics Schematics - R

(RF) Radio Frequency Transmitter Circuits

100 MHz modulated RF source for FM Band - I needed a frequency reference for tuning up the RS-232 to 100 MHz RF desktop channel adapter elsewhere on this site, when I found this Saronix crystal oscillator in my junk box.  A few minutes with VRStudio produced an ATtiny12 to make a tone

10W HF Linear Amplifier

14MHz SSB 10mW Transceiver

175kHz Inductive Pulse Transmitter - This circuit is discussed in more detain in the Experimenters Journal. The transmitter’s six inch diameter coil launches powerful magnetic 175KHz ring pulses that can be detected by the circuit below.

1W Portable PLL transmitter - This small FM transmitter includes a limiter, a microphone amplifier and a PLL digital tuning. All the parts are placed on one circuit board.

2 channel RF remote control - This RF remote control it runs at 418MHz frequency and support up to 2 channels. It is very safety as the transmitting code is changing every time you push any button (roll-code function)

2 Meter Transmitter - This project is a simple transmitter using only one crystal and will cover 145.00 to 146.00 MHz. The crystal is a 44.9333 MHz crystal for 145.500 receive, as used in the Trio (Kenwood) 2200, PYE, Motorola, Tait equipment, to name but four. The frequency of the crystal is not critical as almost any other Xtal for the 2-meter band will function

2 Valve 40m CW Transmitter

2 Valve CW Transmitter

222 MHz Transverter

2m-20m Transverter (transverter) that converts a FT290 or similar multimode handheld transceiver to the 14MHz amateur band. The project is a single board module that needs an external local oscillator, for example, the VHF harmonic oscillator (or QRP VHF FM TX) LO for transverter project. It should be a relatively simple matter of scaling coils

2N2222 40 Meter CW/DSB Tranceiver - In spring of 1998, NorCal sponsored a contest to design and build a project using no ICs and 22 or fewer 2N2222s as the active semiconductor devices. I thought this was a really intriguing idea

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

3 Channel RF Remote Control - This is a 3 channel RF remote control project.The transmitter powered by 3V battery (coin size) range about 10 m. This remote control I use PIC12F509 from Microchip which is a 8-pin single-chip microcontroller designed for low pin count applications with 1 K words flash memory and 41Byte SRAM and some special features such Power-saving Sleep mode, Wake-up from Sleep on pin change

30 Meter QRP Transmitter for Morse Code - This transmitters' intended purpose is for morse-code only in  30 meter band (Tony van Roon's 10Mhz).  It is a low-power QRP type and needs to be connected to your existing transceiver.  harmonic rejections on  prototype were measured at 40dB on 20Mhz and 50dB on 30Mhz

3W HF QRP Linear Amplifier

4 Channel RF AVR Remote Control - How many times you needed some remote control to handle some electric device ? many times. There are lot of remote controls like infrared, RF, SMS (like my other circuit) and more. The basic small-range remote controls are 2, Infrared and RF (Radio Frequency). One of the weaks of Infrared is that the signal can not pass the walls. So, if you want to control your garage door, the only way is to use some RF remote control. The circuit (transmitter and receiver) use few components and ordinary (I love few component circuits) . Its easy to build it because you don't have to tune-up any coil or variable capacitor. The RF modules are fix to work in 418MHz area.

4 MHz Amplitude Modulated RF Source - A while back I needed an amplitude modulated signal source at 4 MHz. This circuit was literally thrown together with parts laying on the bench. I built it dead bug style on a piece of copper clad board. It should work with little or no modification, other than get it to oscillate, and at higher frequencies, you might have to reduce the capacitor values a little.

4 Transistor FM Transmitters (Andy Collinson) -  have used a pair of BC548 transistors in this circuit. Although not strictly RF transistors, they still give good results. I have used an ECM Mic insert from Maplin Electronics, order code FS43W. It is a two terminal ECM, but ordinary dynamic mic inserts can also be used, simply omit the front 10k resistor

4 Transistor Transmitter

49MHz Walkie Talkie - Lots of people are requesting walkie-talkie and RF remote control schematics, so here is some. Building se circuits needs special equipment and expertise in RF circuits. If you are going to experiment with se circuits, please note that I did not build....

4W FM Transmitter - Don't be fooled by  relative simplicity of this transmitter. With 4W of power, it's not a toy! Since it operates in  FM band (88-108MHz), a license is required for broadcasting. With a good and properly mounted antenna this baby has a range of up to 50km. In mountainous terrain or in built-up areas, this figure is smaller, of course.  circuit is fairly small.….

5 Watt 80 Meter QRP CW Transceiver - A great deal of interest has been generated by my previous design articles, so I decided to go to work on a full blown transceiver design. After several months of work, the ROSE-80 transceiver was born. This transceiver is similar to other designs but contains some unique differences.

500mW HF Linear Amplifier

60W Linear Amplifier - This is a RF Linear amplifier for QRO using power mosfet IRF840 with power out 60 Watts. It's simple all solid state circuit.

8 Channel RF Remote Control - This is an 8 Channel RF Remote Transmitter and Receiver that will allow to remotely control various electronic projects. RF Remote Control provides 2 latched and 6 momentary outputs that could be used to control your favorite devices such as amplifier, robotic devices, RC cars, computer, home appliances, lamps and many other cool gadgets.

80 Meter DSB Transmitter

807 & 1625 Valves - data on vacuum tubes 807) and 1625 used in ham radio transmitters. Describes various pin voltages and different operation modes.

A Basic RF Transmitter for PIR Sensors

Active FM Antenna Amplifier - This amplifier will pull in al distant FM stations clearly.  The circuits is configured as a common-emitter tuned RF preamplifier wired around VHF/UHF transistor Q1

AM/FM/SW Active Antenna - This circuit shows an active antenna that can be used for AM, FM, and shortwave SW. On  shortwave band this active antenna is comparable to a20 to30 foot wire antenna. This circuit uses receivers that use untuned wire antennas, such as inexpensive units and car radios.

Analysis of NMR/MRI Coils using PIN Diode Switches

Assorted RF circuits

ATV Repeater Controllers

Automatic message sender for CB

Automatic Repeater - This circuit will be of interest to  radio amateur and anyone possessing two radios, (one of which must be able to transmit i.e. a transceiver). It is a self powered (audio derived) repeater circuit for receiving a signal and re-transmitting it via or radio.

Basic RF Oscillator #1 - This basic circuit is easy to build and the components are not critical.  Most of them can be found in your junk parts box

Building a Simple LF Exciter

Building an RF Remote Control System

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