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Improved Active Antenna - The first 10 mH inductor used in the prototype has about 100 ohms of resistance and that resistance is important in the source of the first J309. if you inductors are significantly lower in resistance, add a series resistor to total around 100 ohms. The other two chokes in the power supply should be below about 100 ohms, but lower resistance is fine. Lower value chokes can be used, but at some point, the low frequency response will suffer. For 100kHz and above, 1 mH is good. Also make sure that the lower value choke exhibits 100 ohms of resistance in the source of the JFET by adding series resistance. __ Contact: Charles Wenzel of Wenzel Associates, Inc. Improved CMOS
RF PLL Sythesizer - Lock range extended up to about 400:1 (50KHz, 2MHz). Spectral purity improved, reduced reference frequency FM ripple. Output level buffered to over 200mW RF power output. Unecessary DiP switches removed, silly combinations not possible. BMP format single-sided PCB foil available for downloading. External VCO/Prescaler PCB to follow shortly (up to 150MHz) __ Designed by Harry Lythall-SM0VPO
Improved Infrared Receiver with status led - This is a general purpose serial port infrared receiver. With the help of appropriate software (see below) you can control different functions of your pc from a distance. For example you can control your home cinema settings (volume, play, pause, stop etc) , your winamp etc __ Contact IQ Technologies
Improved One Tube FM Tuner - in view of the poor performance of the above receiver, I modified the designStill using a 6C4, it is about the simplest valve receiver for FM __ Contact blehack @ yahoo dot com
Inductive Pulse Receiver (175Khz) - This circuit is discussed in more detail in the Experimenters Journal. The receiver’s six inch diameter coil detects the ring signal from the above transmitter and use a single NPN transistor to provided enough amplification for the signal to be easily viewed on an oscilloscope . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2000
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. Design by Angus McCamant
Infrared Receiver for Sony Remotes - infrared remote controls are using a 32-56 kHz modulated square wave for communication. These circuits are used to transmit a 1-4 kHz digital signal (OOK modulation) through infra light (this is the maximum attainable speed, 1000-4000 bits per sec). The transmitter oscillator runs with adjustable frequency in the 32-56kHz range, and is being turned ON/OFF with the modulating signal, a TTL voltage on the MOD input. On the receiver side a photodiode takes up the signal. The integrated circuit inside the chip is sensitive only around a specified frequency in the 32-56 kHz range. The output is the __ Designed by Peter Jakab
Infrared Remote Extender Circuit - This circuit is designed to be placed directly in front of a standard TV or VCR remote. The exiting light pulses produced by the circuit match the pulses from the remote but are about 10 times more powerful . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000
Interference Canceller - This is a Radio Astronomy Project __ Designed by Radio-Sky Publishing
IR Music Transmitter & Receiver - Using this circuit, audio musical notes can be generated and heard up to a distance of 10 metres. The circuit can be divided into two parts: iR music transmitter and receiver.__ Electronics Projects for You
IrDA Serial Receiver - This is a simple serial port irda receiver. __
Jaycar AA-0474 Valve Amplifier (Part 1) - it looked nice and the price was right, but this Chinese vacuum tube amplifier turned out to be a fake __ Contact blehack @ yahoo dot com
Jaycar AA-0474 Valve Amplifier (Part 2) - The fake amplifier is rebuilt as a real valve power amplifier __ Contact blehack @ yahoo dot com
Jupiter receiver notes. KISS mixer - Notes on a few experiments for my Jupiter receiver. __ Contact Vasily Ivanenko
KD2BD ATV AM Video Modulator - video signal processing circuit that allows adjustment of video gain, video bias, sync and sync level__
Keep Wandering Children & Pet Nearby - 12/02/10 EDN Design Ideas: The receiver circuit in Figure 1 sounds an audio alarm when the transmitter (Figure 2) moves beyond a designated perimeter. The transmitter, a voltage-controlled oscillator, operates at approximately 915 MHz in the unlicensed iSM (industrial/scientific/me Design by Tom Au-Yeung and Craig Sakamoto, Maxim Integrated Products, Sunnyvale, CA
Kenwood TH-D7 NMEA GPS bug fix - Almost all APRS enthusiasts know that earliest version of this popular Kenwood transceiver is not always compatible with latest GPS models. We found a solution. __ Designed by Andrea IW9HJV and Johnny IW9ARO
Kenwood TR-7950 manual & Schematics - Being used in a mountain-top repeater, our TM451 transceivers suffered severe frequency shifts as the temperature varied. They are exposed to temperatures as low as -15C in winter and as high as 45C in summer, and the original crystal oscillator is too sensitive to this variations. We measured the repeater to be as high as 2.5Khz up or down in frequency depending on ambient temperature, and we looked for a solution. __ |
