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Control Circuits

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Last Updated: October 24, 2017 02:54 PM

Circuits Designed by Dave Johnson, P.E.

Replace a Pushbutton Switch with this Infrared Safety SwitchUsing a slotted optical sensor, this circuit can be used as a replacement for a large mushroom pushbutton safety switch . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006

Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

Remote-Controlled Power- Off Switch -  Remote controllers for various audio/ video systems are usually provided with a power ‘on’/‘off’ or standby-mode selector button.  But turning the system off from the remote handset actually does not cut...__ Electronics Projects for You

Remote-controlled Preamp with Digital Pot -  This circuit is a simple but high-quality preamplifier using a DS1882 digital potentiometer, a device specially designed for audio applications.  The potentiometer is controlled over an I2C interface by an R8C/13 microcontroller.  The main features of the design are its remote control and lack of moving partsmust register on this site __ Designed by Published in Elecktor July/Aug, 2010

Remote-Controlled Smartfan using AT89c2051 -  The remote-controlled smartfans available in the market are very expensive and their operating principles are difficult to understand.  Here is a simple circuit for a remote-controlled smartfan that can control the...__ Electronics Projects for You

Remotely Programmable RTC Interfaced Microcontroller for Multiple Device Control -  This project based on Atmel AT89C52 and Dallas real-time-clock (RTC) chip DS12887 can be used to control and remotely program the switching operation of 24 electrically operated devices.  The devices can...__ Electronics Projects for You

Remote-Operated Master Switch -  Generally, a bedside master switch is used to switch on lamps both indoors and outdoors when there is a threat of intruder.  This circuit can be used to activate the master...__ Electronics Projects for You

Remote-Operated Musical Bell -  This infrared light controlled 12-tone musical bell can be operated using any TV remote control.  It can be operated from up to 10 metres, provided the remote control is directed towards...__ Electronics Projects for You

Repetitive trigger -  Based on the 555 timer IC, useful for strobe lights.  A bit on the 4017 counter IC for multiple flashes and sequences of flashes __ Designed by Don Klipstein

Replace a Pushbutton Switch with this Infrared Safety Switch -  Using a slotted optical sensor, this circuit can be used as a replacement for a large mushroom pushbutton safety switch . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006

Reset an SOC Only When Power Is Ready -  3-Dec-09 EDN-Design Ideas Use a comparator, an AND gate, and a capacitor to properly reset an SOC __ Circuit Design by Goh Ban Hok, Lantiq Asia Pacific Pte Ltd, Singapore

Reset provides snappy action -  04/29/99  EDN-Design Ideas NOTE :  Scroll to find this circuit.  The circuit in Figure 1 provides a 1-sec reset, using multiple AND gates for increased fanout. Intended for breadboarding or prototyping, the circuit generates a "snappy" master reset that remains active long enough to eliminate questionable start-ups. __ Circuit Design by Steve Kelley, Protoby te Inc, Liberty, MO

Reset supervisor waits for stable supply -  17-Apr-03 EDN-Design Ideas Get more power with a boosted triodeThe power-up cycle of the supply voltage in embedded-system applications is sometimes not a clean event.  This fact holds especially true in battery-operated systems, because the insertion of a battery often causes significant ringing or glitching on the supply line(Figure 1).  In products with on-off switches, the contact bounce of the switch can cause an unclean power-up __ Circuit Design by Mike Mitchell, Texas Instruments, Dallas, TX

Resistor Network Sets Gain for Fixed-Gain Differential Amplifier -  7-Jan-10 EDN-Design Ideas Get the right amount of gain for your op-amp application __ Circuit Design by Miles Thompson, Maxim Integrated Products, Sunnyvale, CA

Resistor packs eliminate temperature drift -  06/19/97 EDN-Design Ideas Finding low-temperature-coefficient resistors for 10-bit or more accurate analog applications is often a problem in the laboratory.  Even if you have a good collection of precision, low-temperature-coefficient resistors in stock, chances are they won't track across even room temperatures. __ Circuit Design by Jim Hansen, Kollsman Inc, Merrimack, NH

Resistor-Switch Networks for Audio Volume Control -  The traditional potentiometer is implemented with an electrical contact that slides over a resistive layer.  An example of a well-known audio-grade potmeter is the Alps Blue.  I still use this one myself.  A high-end (good and costly) alternative is the rotary switch.  This device consists of a series of discrete resistors and switches, of which always one switch is actually closed.  Resistor-switch networks can offer advantages over the potentiometer such as: * Improved quality of the electrical contact, in comparison with the slider.  * Improved consistency between separate audio channels (stereo or multi-channel) * Less sensitive to dust and wear.  

Resolving Very Small Temperature Differences with the LTC2402 -  DN257 Design Notes__ Linear Technology/Analog Devices

Restaurant Menu Ordering SystE - M -  Automation systems are increasing in day to day life.  Applications like home and industrial automation reduce man power while increasing the efficiency.  Here in this project let us see how automated menu for ordering...__ Electronics Projects for You

Reverse RIAA Equaliser -  Test phono preamps for correct equalisation, or convert unused phono inputs.     __ Designed by Rod Elliott  ESP

RF Remote Control SystE - M -  With a handful of inexpensive components, a little creativity, and the power of PicBasic, you can build some pretty outstanding robotics creations as Rob Arnold proves with his Ruf-Bot project.   __ Designed by Rob Arnold

RF Wireless PWM DC Motor Speed control -  The wireless PWM DC motor transmitter circuit consists of WZ-X01 RF module, Holtek HT-640 encoder and 8-bit A/D converter.  U1 ADC0804 converts the analog voltage to digital data; U2 encodes that data (D0~D6) along with D6, D7 and transmitting through the RF transmitter module.  The potentiometer VR1 varies the voltage to the A/D U1 pin6,  __ Contact: info @ wzmicro.com

Ring your bell; light your light -  11/11/99 EDN-Desgin IdeasThe circuit in Figure 1 provIdeas a simple and inexpensive way to provide illumination for a dark doorway.  Pressing the doorbell button momentarily rings the doorbell and turns on the porch light.  The porch light remains on for approximately 25 sec and then turns off.  This interval is long enough for a person to find his or her way when it's dark.    __ Circuit Design by Dennis Eichenberg

Ring-Around LED Flasher -  This schematic diagram shows a ring-around LED flasher circuit.  This circuit will turn off two LEDs and turn on the other two until the timing cycle reverses.  This circuit can be configured to flash four LEDs in sequential order  by pressing and holding S1 closed until only one of the LEDs is on then releasing it.

Ringing Phone Light Flasher -  This is very useful in a situation were there is lots of noise and it is impossable to hear the phone, such as a workshop.  Here is such a device.  The ring detect part of this circuit came from [url]http://www.  hut.  fi/Misc/Electronics/circuits/telephone_ringer.  html[/url].  Notes: 1.  You may need to use a lower voltage zener for D1 and D2.2.  You can use a regular relay instead of a solid state relay, but the arcing accross the contacts may destroy it pretty quickly.3.  Be very sure that you have not accidentally connected 120V to the phone line when building and installing this __ Designed by Aaron Cake

Robotic MicroController Board -  Schematic only, no circuit description included

Rolling Code 4-Channel UHF Remote Control -  It has a long range, its rolling code is virtually unbreakable, it uses a keyring transmitter and it's ideal for use with garage door controllers.__ SiliconChip

Rolling Code 4-Channel UHF Remote Control -  It has a long range, its rolling code is virtually unbreakable, it uses a keyring transmitter and it's ideal for use with garage door controllers. __ Designed by Frank Crivelli & Peter Crowcroft

Room heating controller -  Tired of mechanical thermostats that overshoot the set point and make you waste expensive energy? Here is a phase-control device that works well and is simple! __ Designed by Manfred Mornhinweg

Room Monitor -  This circuit allows audio monitoring of a remote location and so doubles as a room monitor or baby alarm.  It can be run from a 12 Volt battery or mains power supply as shown below.  Interconnect uses 3 wires, so multi core cable can be used; alarm or telephone cable is suitable just leave any extra wires free __ Designed by Andy Collison

Room Sound Monitor -  With this simple circuit, you can secretly listen to conversations going on in a room.  The circuit is very sensitive and powered by a 3V battery.  The working of the circuit is...__ Electronics Projects for You

Room temperature controller -  On this page, I will introduce the room temperature controller with PIC.  This equipment uses two temperature sensors, drives external equipment, and keeps the temperature of the room at preset temperature.  The purpose of this equipment is for preventing room temperature going up with the heat of the computers.  Electric cost will become high if an air-conditioner is always operated.  Then, I made the equipment __ Designed by Seiichi Inoue

Rotary Controller Positions Stepping Motor -  EDN-Design Ideas 08/03/95    The circuit in Fig 1 uses a servo potentiometer, as opposed to a rotary switch or encoder, to provide the necessary drive pulses for a stepping motor.  This motor positions a pointer by the rotation of a manual control.  The circuit must be precise, allow a rapid response, and be simple to use.  (This circuit was part of a complex apparatus used for a series of physiological tests.) Another requirement is that the control had to be a small, handheld, battery-operated device.    __ Circuit Design by TG Barnett and ME Rosenberg, Department of Physiology, Queen Mary and Westfield College, London, UK-- 08/03/95

Rotating & Flashing 230V Lights -  This design can be of some interest for those wanting striking light signs, as it can drive up to three 230V lamp strings in three operating modes.  The 15V dc supply is obtained from a nominal 230/24V center tapped ac transformer   (T1) and a full wave rectifier __ Contact: Flavio Dellepiane, fladello @ tin.it

RS-232 Transceiver with Automatic Power Shutdown Control -  DN30 Design Notes__ Linear Technology/Analog Devices

RS232c Level Converter -  A circuit for RS232C level converter, MAX232 and DS275 __ Designed by Wichit Sirichote

RS-232C port scans remote keypA - D -  12/04/97 EDN-Design Ideas In many embedded or control applications, you might prefer to use a small, customized keypad with your PC-based system rather than a full-fledged alphanumeric keyboard.  You may also need to locate the keypad some distance from the system hardware.  If you have __ Circuit Design by SK Shenoy, NPOL, Kochi, India

RS-485 for Digital Motor Control Applications -  Small electromechanical drives include solenoid drives, single direction DC, bi-directional DC, or brushless DC systems and are typically sized according to their frame size and power in watts.  Digital controllers, software, and complimentary analog and digital solutions from TI can help solve most drive requirements.   __ Designed by Texas Instruments App Notes, 12-May-03

Rules of Thumb Aid in Timeconstant Analysis -  11/07/97 EDN-Design Ideas An RC circuit charges or discharges to within 36.8% of the total excursion in one time constant, t, where t=RC.  However, 36.8% is an awkward figure, and you usually need a calculator to achieve reasonable accuracy.  You need a sho __ Circuit Design by Tony Zizzo, Burr-Brown, Tucson, AZ

Running LED -  Just for fun I designed and tested two running LED circuits based on CD4017.  The first one drives a strip of six LED, while the second one works for a strip of eight LED.  Both circuits work in bidirectional running __ Designed by Andrea-Central Italy

RX/TX 27 MHz Wireless Remote Control -  Schematic only __ Designed by va3iul

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