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Digital  / Logic Circuits 
Digital Circuits:   #'s - C       D - G       H - M       N - R       S - T       U - Z

Last Updated on: Thursday, November 30, 2017 04:23 PM

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

R/C Digital Camera Controller -  My personal experience with R/C airborne video is focused on wireless video systems that transmit realtime images.  However, airborne still photography is quickly becoming a popular alternative, especially since it avoids all the FCC/ham license issues.  And the new mega-pixel digital cameras are low cost and are surprisingly small.  Nearly any model aircraft can haul one around.   __ Designed by RC-CAM T. Black

Railpower Model Train Controller -  This ultra-high performance model train controller features infrared remote control.  We believe it's the best build-it-yourself train controller ever published!__ SiliconChip

Railpower Model Train Controller, Pt.2 -  Last month we presented the circuit, specifications and parts list for our new high-performance Railpower IV model train controller.  Now it's time for the construction detailsand we show you how to set it up for best performance.__ SiliconChip

Railpower Model Train Controller; Pt 2 -  Final article describes the IR remote control circuit and gives the full construction details.__ SiliconChip

Random Numbers -  PIC Project  Many random number generators are software versions of the hardware shift register feedback circuit.  Two problems with this approach are that this operation is usually clumsy in software and the results have some noticeable patterns.   __ Designed by Luhan MonatMesa Arizona

Random-Bit-Sequence Generator -  05/10/01  EDN-Design Ideas A random-bit-sequence generator is basic equipment for prototyping and testing any data-transmission system.  You use such a generator when measuring BER  (bit-error rate) and pattern-dependent effects in a transmission system.  Such effects can include base __ Circuit Design by Przemyslaw Krehlik

Random-Number Generator Prefers Imperfect Clock -  11/21/96  EDN-Design Ideas The circuit in Figure 1 generates random numbers using a linear-feedback shift register  (LFSR) .  The 16-bit LFSR consists of two shift registers, IC3 and IC4, and the feedback circuitry comprising IC5A, IC6A, and IC6B.  The CLK2 signal clocks the output of __ Circuit Design by Sergey Velichko, SCP Global Technologies, Boise, ID

Rapid Prototyping Speeds Development of UMTS W-CDMA Algorithms -  Application Note__ Aligent

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

Reader/Programmer for Smart Cards -  Low-cost Phoenix-type reader/programmer lets you program your own Smart Cards for all kinds of applications.__ SiliconChip

Reading Data from the Parallel Port -  The diagram below shows 5 switches connected to the 5 input lines of the parallel port.  An external 5 volt power supply is used to provide high logic levels to the input pins when the switches are open.  Three 1.5 volt batteries in series can be used to obtain 4.5 volts which is close enough.  The 330 ohm resistors.   __ Designed by Bill Bowden

Reflective Object Sensor Works In Bright Areas -  07/29/10 EDN-Design Ideas Digital logic lets you accurately detect a passing object, even under a bright light.    __ Circuit Design by Vladimir Rentyuk, Modul-98 Ltd, Zaporozhye, Ukraine

Regulated High-Voltage Supply for Valve Amplifiers -  How to modify a surplus PC power supply to produce a 700V or 400V high-voltage rail.__ SiliconChip

Relative-Humidity Transmitter uses Single Logic IC -  11/08/01  EDN-Design Ideas The low-cost percentage-relative-humidity radio transmitter in Figure 1 operates in a cold-storage warehouse for vegetable storage at temperatures of 1 to 5C.  It is generally difficult to collect such data from a low-temperature ar __ Circuit Design by Shyam Tiwari, Sensors Technology Ltd, Gwalior, India

Remote digital thermometer sends data over AC power line -  This circuit is a simple oscillator.  It's frequency is in the range 35 kHz60 kHz and it' s adjustable.   __ Designed by Ali Alipour.ralipoor90 @ gmail.com

Remote Infrared Terminal -  This unit provide 2 way IR communications using a numeric keypad and an LCD display.  Data is sent and recieved in ASCII with no regard to what the data means to any particular device __ Designed by Luhan MonatMesa Arizona

Remote Mains Relay Mk.2 -  The PC board used for the USB Sensing Power Switch can also be used to build a remote mains relay.  This can be used for switching mains power to lights or appliances using a remote switch  (or relay) linked by low-voltage wiring.  It can also be used for controlling security lights from the relay contacts on a PIR sensor.__ SiliconChip

Remote RF Xmiter -  This device was built into a small  (1 1/4 by 2 inch) Radio Shack project box.  It features four push buttons which can produce 2 codes each.   (Pushing a button for less than one second sends the first code, holding it for over one second sends the second code.)  __ Designed by Luhan Monat-Mesa Arizona

Remote Telltale for Garage Doors -  If you have a perfect memory you won't need this.  But the rest of us could find it very handy! It lets you know if you've left the garage door open without stumbling out in the dark or the pouring rain...__ SiliconChip

Remote Thermometer -  This circuit is intended for precision centigrade temperature measurement, with a transmitter section converting to frequency the sensor's output voltage, which is proportional to the measured temperature.  The output frequency bursts are conveyed into the mains supply cables.  The receiver section counts the bursts coming from mains supply and shows the counting on three 7-segment LED displays.  The least significant digit displays tenths of degree and then a 00.0 to 99.9 C range is obtained.  Transmitter-receiver distance can reach hundred meters, provided both units are connected to the mains supply within the control of the same light-meter.   __ Contact: Flavio Dellepiane, fladello @ tin.it

Remote Volume Control & Preamplifier Module -  This up-to-date control module works with any universal infrared remote and features a blue LED readout and an optional rotary encoder.  Its ability to both attenuate and amplify means that it can operate as a simple volume control or as a high-performance stereo preamplifier!__ SiliconChip

Remote-Controlled Automatic Table Lamp Dimmer -  It automatically dims up or down between two preset levels or you can manually control the lamp brightness, all via remote control__ SiliconChip

Remote-Controlled Digital Up/Down Timer -  This remote-controlled digital timer has a bright 20mm-high 7-segment red LED display & can count up or down from one second to 100 hours in 1-second steps.  Its timing period can either be set and controlled using the remote control or it can be automatically controlled via external trigger/reset inputs.  An internal relay and buzzer activate when the unit times out.__ SiliconChip

Replace an External Gate with a Resistor -  08/17/98 EDN-Design Ideas NOTE :  File has several circuits, scroll to this one.  You can significantly reduce costs in a single-chip C application by replacing an external gate with a resistor.  In applications that require the gating of an external signal for measurement purposes, the traditional circuit uses an external two-input AND gate (Figure 1a) .  An I/O line __ Circuit Design by Stan D'Souza, Microchip Technology Inc, Chandler, AZ

Replacement CDI Module for Small Petrol Motors -  If the CDI module in your motorbike, outboard, ride-on mower or other small petrol motor fails, you could be in for a shock.  Depending on the brand or model, they can cost up to $400.  You can build this one for less than $50 and it will do the same job for most engines.__ SiliconChip

Resistor Substitution Box -  PIC Project  Commercial substitution boxes uses a lot of switches and a set of fixed resistors.  The advantage is that they have a large range of resistance and work at higher voltages.  This device is only good for use in circuits of 12 volts or so but it is much smaller and cheaper.  It uses a log taper 2 watt potentiometer  (Digikey part# KA1031S28) to produce a range of resistance values from about 50 ohms to 10k ohms.   __ Designed by Luhan MonatMesa Arizona

Resistors In Digital -  EDN-Design Ideas 02/02/95    When I was a young technician, my associates and I arrogantly believed we could build anything with enough 10k resistors and duct tape.  Now it seems that even simple electronic toys use several million transistors encased in tiny SMT packages with hundreds of hairlike leads; no one talks about discrete components anymore.  Yet, no matter how digital our embedded designs get, we cannot avoid certain fundamental electrical properties of our circuits.  For example, somehow the digital age has a greater and ever-increasing need for resistors-so many, in fact, that most "discrete" resistors are now  __ Circuit Design by Jack Ganssle, Embedded-Systems Contributing Editor

Reverse Loop Controller for DCC Model Railways -  Another project for DCC Model Railway enthusiasts...__ SiliconChip

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

RGB to Component -  What- no RGB inputs on your TV to match your new digital set-top box? Don't sweat it....build this low cost unit instead.__ SiliconChip

Ride the logic thresholds -  08/03/00 EDN-Design Ideas  Most logic devices have a 5V supply rail.  However, you often need to know the upper and lower switching thresholds for a device operating at supply levels other than 5V.  In some cases, it is also important to know the variation of these thresholds with supply voltage.  A simple test circuit allows you to make these measurements  (Figure 1)  __ Circuit Design by Roger Griswold, Maxim Integrated Products, Sunnyvale, CAAugust 3, 2000

RLCs match transmission lines to loA - D -  04/10/97 EDN-Design Ideas In many systems, transmission lines drive reactive  (mostly capacitive) loads.  To preserve signal integrity, you should properly terminate the lines.  However, the input impedance of CMOS logic ICs, for example, comprises a high resistance in parallel with capacitance.  A mismatch at the lines end causes reflections and pulse-shaped distortion.  You can use simple RLC circuits to compensate for the mismatch.  In RF designs, the goal in matching impedances is to transfer power with maximum efficiency.   __ Circuit Design by Boris Dvoskin, Worcester, MA

Roach Motel-Electronic -  Using a PIC for this device provides a lot of useful functionality.  The timing for the power pulse to the inductor is critical to getting the best Zap from your nine volt battery.  The longer the current is on, the higher the voltage.  Once the inductor reaches saturation, however, you are just waisting power.   __ Designed by Luhan MonatMesa Arizona

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 Security System; Pt 1  -  Ideal for keyless entry for doors in cars, homes & industry, this Keyless Entry System features a rolling code to ensure high security.  It also has two door-strike outputs, an alarm system & provision to use up to 16 separate keyfob transmitters with the same receiver.__ SiliconChip

Rolling Code Security System; Pt.2 -  Last month, we described the circuitry and gave the PC board assembly details for our new Rolling Code Keyless Entry System.  This month, we cover the installation and setting-up procedures and describe the optional SOIC adaptor board, so that you can program the PIC micro out of circuit.__ SiliconChip

Rolling-code generator uses flash microcontroller -  05/03/01 EDN-Design Ideas Many security-alarm systems require the use of a random number.  A computer program uses this random number to create a sequence of random numbers to prevent unwanted visitors from gaining entry into a protected facility.  You can use a "rolling-code generator" to produce random numbers.  To implement such a generator, you would typically need a microcontroller with external memory.   __ Circuit Design by Wallace Ly

RoomGuard: a Low Cost Intruder Alarm -  Simple design interfaces to a battery-powered smoke detector.__ SiliconChip

Rotary Encoder Mates with Digital Potentiometer -  6-Mar-03 EDN-Design Ideas Buck IC boosts battery voltage for white LEDIn developing electronic systems, designers look for products or ideas that may benefit from the better performance, smaller size, lower cost, and improved reliability that an IC can offer.  Toward that end, the digital potentiometer emerged as an alternative to its mechanical counterpart, the mechanical potentiometer __ Circuit Design by Peter Khairolomour, Analog Devices, San Jose, CA

RS-232 Interface to PIC -  PIC Project  The standard rs-232  (com port) interface specifies +/- 12 volt signals.  It is possible to work quite well with +/- 5 volts.  This circuit works by 'stealing' the negative voltage from the COM port and using it to communicate back.   __ Designed by Luhan MonatMesa Arizona

RS-232 to TTL Cable -  A common feature found on many Microcontrollers is a serial port  (often called a SCI, COM, or ASYNC port) .  I am going to use the term SCI as a short cut to mean the serial port on your Microcontroller.  Quite often, the SCI on your Microcontroller will generate the appropriate LOGIC signals to communicate with another chip.  They do not, however, generate the proper voltages required for connecting to RS-232 devices.  This article is going to describe the differences between RS-232 and TTL, and how to build a converter so you can connect your Microcontroller to an RS-232 compatible device, such as the COM port on your PC. __ Designed by Kevin Ross

RS-232 to TTL Translator -  A simple terminal program on a PC can have a lot of uses.    The hang-up is that most of those uses involve communicating with a device running on 5 volts.    I've done several schemes over the years but this one is my favorites.   __ Designed by Luhan MonatMesa Arizona

RS485-Like Multi-Drop Bus with Half Duplex Serial Protocol -  PBUS is an RS485-like multi-drop bus for interconnecting PIC and other microcontroller-driven devices.  Protocol and software is written by Jap.  Just include a separate pbus library file into your project and add your command handlers for the specific device in a few lines __ Designed by Peter Jakab

Rudder Position Indicator for Power Boats -  Part 1__ SiliconChip

Rudder Position Indicator for Power Boats, Pt.2 -  Last month we introduced our Rudder Position Indicator, which uses a 433MHz wireless link to show the direction a power boat?s rudder is pointing.  This month we provide detailed instructions for building and testing both units as well as mounting the sensor unit in the boat.__ SiliconChip

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Digital or Logic Circuits:  #'s - C       D - G       H - M       N - R       S - T       U - Z

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