Variable RF attenuator with PIN diode

Variable RF attenuators are often used to control the level of a radio frequency signal using a control voltage in RF design. These variable RF attenuators can even be used in programmable RF attenuators. Here the known voltage generated by a computer for example can be applied to the circuit and in this way create a programmable RF attenuator.Often...

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Power Supply with Short Circuit Protection 13.8V 30-40A

Here's a safe power supply with short circuit protection. The power supply is build around the LM723 controller and four BUZ24 (or IRF150) power N-Channel FET transistors. FET transistors are used because of the simplicity of controlling the current through these transistors, it's simply voltage controlled, and because of the low power consumption...

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RF Power Meter Reading by Digital Voltmeter

The RF Power Meter circuit is based on the AD8313 Log Detector manufactured by Analog Devices. In GSM phones AD8313 is used as a Log Detector, part of the Power Control Loop circuit. Generally could be easy identified near the Power Amplifier module.AD8313 is a Logarithmic Detector which can accurately convert an RF signal at its input to...

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25W Broadband RF Amplifier 88-108 MHz

This RF amplifier for FM 88-108 MHz with no tune (broadband) needed to cover all the FM Band. This RF Power amplifier is equiped with the famous Mosfet transistor the BLF245. Depending on the output power level you are able to provide with your FM synthesizer, you can use or not the 2N3866 driver stage included in this amplifier design.Impedance...

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Another K1 Build - this one will be mine this time.

Various shots going through the RF Part I build. The Front panel and filter board already built.The extensive home brew ben...

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FtTuthill80 Build

Kits components as sent.Following the pdf instructions of Dan Tayloe, N7VEThese are the build images from the kit I just started to build.Up to the power test (used a 9V battery) and the blue LED lighting.Blue LEDDiodes Sorting the 0.1uF caps0.1uF capsMore capsAnd moreElectrolyticsResistorsMore resistorsMore resistorsApplying 9V.The LED lights...

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Elecraft T1

Was recently given an Elecraft T1 auto tuner kit and as now working in Belgium thought I'd make it up. First started in hotel room..The portable 'homebrew' bench is perfectly adequate. Note I have brought a 12" square of PCB to build on.Initial components going in.Relays fitted.Fitted the underside capacitor.Fitted the sockets and headers.Built...

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USB FM Transmitter for MP3 Player

This MP3 Player FM transmitter can be used to listen to your own music throughout your home. The transmitter circuit use no coils that have to be wound. When this FM transmitter used in the car, there is no need for a separate input to the car stereo to play back the music files from your MP3 player. This FM transmitter use a chip made by...

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USB Powered FM Transmitter Circuit

The radio is a very simple media. Just a few electronic components able to transmit on the FM band. Aside of course, make these frequencies is illegal. This FM transmitter, which is powered by USB, recovers output on your computer or your MP3 player to the relay on the tape FM (frequency 108 MHz).For Assemblying this FM transmitter kit, a...

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Super J-Pole VHF Antenna Design

Here's the super J-pole antenna design that is a regular J-pole antenna with a 1/2 wave element mounted above with a 1/2 wave phasing harness connecting the element to the bottom part of the J-pole. The antenna can be built for any band.This J-pole antenna is made with copper pipe. The phasing harness is made from large diameter copper...

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