QRP Longwire balun -  Ham RadioBALUN, TUNERSSchematic __ Designed by Guy Roels ON6MU

Quad Comparator Regulates Temperature -  10/26/95 EDN-Design Ideas Using a negative-temperature-coefficient thermistor, the circuit in Fig 1a controls temperature within 1°C or better with a minimum of components, cost, and complexity.  The circuit includes protection against a short or open temperature sensor.  You can purchase all of the key components, except the actual heating element, at the local Radio Shack.    Design by H Randall Moore, Lake Forest, CA

Quartz crystal-based remote thermometer features direct Celsius readout -  03/17/05 EDN-Design Ideas Although quartz crystals have served as temperature sensors, designers haven't taken advantage of the technology because few manufacturers offer the sensors as standard products(references 1 and 2].  In contrast to conventional resistance- or semiconductor-based sensors, a quartz-based sensor provIdeas inherently digital-signal conditioning, good stability, and a direct digital ou Design by Jim Williams and Mark Thoren, Linear Technology Corp

R/C helicopter camera -  Although the RC-CAM2 system is no longer used, you will certainly learn a lot by reading the details to building it.  Like many good things, its useful life has come to an end and it has been replaced by the latest project called RC-CAM3.  But for historical benefit, the original RC-CAM2 project is listed below.  Enjoy! __ Designed by RC-CAM T. Black

R/C Pilot -  Circuit + Parts List + Notes __ Designed by Tony van Roon  VA3AVR

R/C Switch -  This circuit is a so-called "Radio controlled Electronic Switch".  It can be used to switch on/off anything electrical, whatever it is.  Here are a couple of examples: navigation lights, landing gear, sound systems, Glowplug driver, bomb release, parachute, search lights, gyros, and so on.  This circuits connects to a RC car controller servo output.   __ Designed by Tony van Roon  VA3AVR

R/C Switch 2 -  Circuit (Adjustable, 20-80 seconds) + Parts List + Notes __ Designed by Tony van Roon  VA3AVR

R/C Switch 3 -  Circuit + Parts List + Notes __ Designed by Tony van Roon  VA3AVR

R/C Switch 4 -  Circuit + Parts List + Notes __ Designed by Tony van Roon  VA3AVR

R/C Switch 5 -  Circuit + Parts List + Notes __ Designed by Tony van Roon  VA3AVR

Race Starter Controller -  A basic sequencer that turns on 5 pairs of LED's at a rate of around 1Hz and sounds a buzzer on the last one to signify the start of a race.  If using a power supply from the scalectrix, be sure it is a regulated supply __ Contact: P. Townshend EduTek Ltd

Radio Control made from Junk -  Here we are going to make a simple radio controlled device using supplies from your local dumpster.  This project should cost less than a dollar to make.  If you spend more than a dollar on this project, you need to dig more.   __ Designed by sixmhz @ yahoo.com

Radio Controlled Battery Backup -  Circuit + Parts List + Notes __ Designed by Tony van Roon  VA3AVR

Radio Controlled Pilot -  Circuit + Parts List + Notes __ Designed by Tony van Roon  VA3AVR

Radio Controlled Switch -  This circuit is a so-called "Radio controlled Electronic Switch".  It can be used to switch on/off anything electrical, whatever it is.  Here are a couple of examples: navigation lights, landing gear, sound systems, Glowplug driver, bomb release, parachute, search lights, gyros, and so on.  This circuits connects to a RC car controller servo output.   __ Designed by Tony van Roon  VA3AVR

Radio Controlled Switch 2 -  Circuit (Adjustable, 20-80 seconds) + Parts List + Notes __ Designed by Tony van Roon  VA3AVR

Radio Controlled Switch 3 -  Circuit + Parts List + Notes __ Designed by Tony van Roon  VA3AVR

Radio Controlled Switch 4 -  Circuit + Parts List + Notes __ Designed by Tony van Roon  VA3AVR

Radio Controlled Switch 5 -  Circuit + Parts List + Notes __ Designed by Tony van Roon  VA3AVR

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 __ Designed by Radioland.net

Railway Model Train Controller Pt 3 -  As promised in part 2, here is the walk-around throttle version of the Railpower speed control for model railways.  It uses four switches to control speed, forward/reverse, inertia and braking.__ SiliconChip

Ramping Lamp Driver -  This circuit drives any 12v lamp, incandescent or LED type, in a ramping fashion.  Each press of the button toggles the lamp from a fully off mode to a fully on mode.  But, instead of an instantaneous lamp intensity change, the power is slowly ramped up a . . . Hobby Circuit designed by Dave Johnson P.E.-December, 2007

Ramping LED Driver -  The circuit below was designed to drive a LED with an intensity ramping mode.  Two 555 timers generate two different triangle waveforms.  The upper device generates a 10KHz signal while the lower unit produces a 1Hz signal.  The two signals are fed to a. . . Circuit by Dave Johnson P.E.-December, 2007

Random' Flasher for 8 LEDs -  This project uses a 4026 counter and display driver IC to flash eight LEDs in an apparently random manner.  It can be used to create a display of your choice.   __ Designed by John Hewes

Rapidly Stops DC Motor Drive  -  This circuit will bring a fast moving DC motor to a stop in seconds.  The braking action is automatically applied whenever DC power is removed. . . Circuit by Dave Johnson P.E.-September, 2004

RC Controlled Digital Camera -  The aim of this project was to get a digital camera into a small electric radio controlled (RC) airplane and still have it fly.  The airplane shown, a park flyer, weighs between 400 and 550 grams depending on the size of battery and wing configuration that I use __ Contact: r dot p @ webone.com.au

RC Low-Pass Filter -  (spice design)  __ Designed by Rick 

RC lowpass filter expands microcomputer’s output port -  06/21/07  EDN-Design Ideas A simple lowpass RC filter allows a single output pin of a microcontroller to expand the number of output bits Design by Rex Niven, Forty Trout Electronics, Eltham, Victoria, Australia

RC network quashes auxiliary winding in quasiresonant converter -  04/01/04  EDN-Design Ideas Quasi-square-wave-resonant converters, also known as QR (quasiresonant] converters, allow the design of flyback-type SMPSs (switch-mode power supplies] with a reduced EMI (electromagnetic-interference] signature and improved efficiency Design by Nicolas Cyr, On Semiconductor, Toulouse, France

RC Notch Filter (Twin T) -  The twin T notch filter can be used block an unwanted frequency or if placed around an op-amp as a bandpass filter.  The notch frequency occurs where the capacitive reactance equals the resistance Xc=R and if the values are close, the attenuation can be very high and the notch frequency virtually eliminated __ Designed by Bill Bowden

RC Receiver Hosts Two Independent Switches -  06/06/96  EDN-Design Ideas Typical inexpensive radio-control (RC] systems have servo-motor outputs, but no on/off switch outputs.  You can add two independent RC switches to a system without making any transmitter or receiver modifications Design by Tom Howell, US Army ARDEC, Picatinny Arsenal, Dover, NJ

RC Servo Tester with 555 IC -  Servo refers to an error sensing feedback control which is used to correct the performance of a system.  Servo motor is a DC motor equipped with a servo mechanism for precise control of angular position.  Servo motors usually have a rotation limit from 90° to 180°.  Servos are used for precision positioning in robotic __ Designed by T.K. Hareendran