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

Last Updated on: Monday, December 25, 2017 01:50 PM

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

Lab-Standard 16-Bit Digital Potentiometer -  No, this is not some kind of fancy digital volume control for hifi systems.  Instead, it's a low-cost digital programmable voltage divider.  It's used to provide an accurate adjustable output from a precision voltage reference for meter calibration and other tasks.__ SiliconChip

Lamp Dimmer-120 VA - C The full wave phase control circuit below was found in a RCA power circuits book from 1969.  The load is placed in series with the AC line and the four diodes provide a full wave rectified voltage to the anode of a SCR.  Two small signal transistors are connected in a switch configuration so that when the voltage on the 2.2uF __ Designed by Bill Bowden

Lap Counter for Swimming Pools -  Do you swim laps to keep in shape? This simple Picaxe-powered counter will keep track of the number of laps you've done__ SiliconChip

LCD 2x16 characters &  4x4 keypad assembly example -  Connect some 2x16 characters LCD display and 4x4 keypad with AVR microcontroller __ Designed by © Vassilis Serasidis

Lead-Acid Battery Zapper -  This simple circuit is designed to extend the working life of liquid-electrolyte lead-acid batteries, by dissolving the lead-sulphate crystals which form on their plates.  It's powered by the battery itself  (or by a charger) and "zaps" the battery with a series of high-voltage pulses.__ SiliconChip

Lead-Acid Battery Zapper & Desulphator Mk.3 -  Here is a revised version of the popular Lead-Acid Battery Zapper featured in the May 2006 issue of SILICON CHIP.  It is now separate from the Battery Condition Checker and much easier to build.  At the same time it has been revamped for more reliable long-period operation with 6V, 12V & 24V batteries.__ SiliconChip

Lead-Acid/SLA Battery Condition Checker -  In July 2009 we presented an improved version of the Battery Zapper & Desulphator.  Here we present the companion Battery Condition Checker.  It gives more stable readings for all three main battery voltages  (6V, 12V & 24V) than our earlier model, as well as giving a choice of test current pulse levels to suit batteries of different capacities.  As a result, it?s now also suitable for testing sealed lead acid  (SLA) batteries.__ SiliconChip

LED & Piezo On One Line using a PIC16c508 -  Scroll to find this circiutOne of the simplest combinations is a LED and Piezo on a single drive-line as shown in fig: 1.  These can be combined because the requirements of a LED are different to a piezo.  A LED requires a constant HIGH for it to illuminate while a piezo requires a HIGH-LOW-HIGH waveform at approx 3kHz to produce a tone.   __ Designed by Prepared Colin Mitchell

LED & Push Button On One Line using a PIC16c508 -  Scroll to find this circuit # 2In this book, we show how to connect two and up to five or more push buttons on a single input line and generally you will not have any problems adding buttons to a project.  But if you want to add a secret reset button  (or a "cheat" button, for example) , it can be added across an existing LED as shown in fig: 3.   __ Contact: Colin Mitchell

LED 9-Second Relay Timer -  This circuit provides a visual 9 second delay using a 7 segment digital readout LED.  When the switch is closed, the CD4010 up/down counter is preset to 9 and the 555 timer is disabled with the output held high.  When the switch is opened,  __ Designed by Bill Bowden

LED AM meter -  Measures current up to 10A with selected 100mA, 10mA and 1mA resolutions.  

LED Christmas Tree with 64 LEDs -  The Holidays are once again upon us and we wanted to give our readers the edge in decorating this year.  Continuing our all-digital-hardware theme to coincide with our Kickstarter for a Digital Electronics Course at PyroEDU, we have created an LED Christmas tree controlled entirely by digital logic __ Designed by PyroElectro

LED Clock with Timer & Solar Panel Regulator -  This is a combination digital clock timer and solar panel charge controller used to maintain a deep cycle battery from a solar panel.  The timer output is used to control a 12 volt load for a 32 minute time interval each day.  Start time is set using 9 dip switches and ends 32 minutes later. __ Designed by Bill Bowden

LED display Digital Voltmeter -  This digital voltmeter is ideal to use for measuring the output voltage of your DC power supply.  It includes a 3.5-digit LED display with a negative voltage indicator.  It measures DC voltages from 0 to 199.9V with a resolution of 0.1V.  The voltmeter is based on single ICL7107 chip and may be fitted on a small 3cm x 7cm

LED Flasher -  LED flasher with the LM3909 IC and runs from1.5-Volt battery.   __ Designed by Tony van Roon  VA3AVR

LED Lighting Effects -  The original yoyo was equiped with 2 LEDs that lit up whendevice was spinning.  I decided to add a micro to give it some extra pazazz.  The trick here is to makeunit work without a power switch.  The mercury switch is positioned so that it supplies power whenunit is spinning.  After about 20 seconds, PIC shuts down in sleep modes,  __ Designed by Luhan Monat-Mesa Arizona

LED Lighting For Dual-Filament Lamps -  Before we describe how it’s done, note that we recommend that the result be checked as having sufficient brightness for a stop & tail-light application.  That’s because the light output may be inadequate, depending on the tail-light lens and reflector assembly – so use any modified lamps with discretion! As shown, an additional diode  (D1) […]

LED Lighting for Your Car -  Replace your car's filament lamps with LED's for improved safety.  There are several designs to build, all using high- brightness LED's.__ SiliconChip

LED Relay Timer -  This circuit provides a visual 9 second delay using a 7 segment digital readout LED.  When the switch is closed, the CD4010 up/down counter is preset to 9 and the 555 timer is disabled with the output held high.  When the switch is opened,  __ Designed by Bill Bowden

LED Strobe & Contactless Tachometer -  This versatile LED Strobe & Tachometer can be used to observe and measure the RPM of rotating machinery.  It offers three different measurement methods and the readout is via a 2-line LCD module.__ SiliconChip

Led Strobe & Tacho Pt.2 -  Last month, we published the circuit of our new LED Strobe & Tachometer and showed how to build the main unit and the strobe light.  This month, we describe the assembly of the optional Photo-Interruptor and IR Reflector Amplifier boards.  We also describe how the unit is used.__ SiliconChip

LED Voltmeter -  Measures voltages up to 199.9V with 0.1V resolution.  

Let's Get Quizzical: a Quiz Game with a Difference -  No more boring old buzzers for us...__ SiliconChip

Li-Ion Charger -  PIC Project  Lithium Ion batteries pack a lot of power by weight compared to other types.  There are 2 things that need to be handled differently than NiCad on NiMH
: __ Designed by Luhan MonatMesa Arizona

Limiting Amplifier is Digitally Programmable -  06/04/98 EDN-Design Ideas To generate high voltages with proper insulation between  "hot node" and  rest of  circuitry, a car ignition coil can function in place of a high-voltage transformer.  se coils have voltage ratings of approximately 20 kV,.    __ Circuit Design by V Manoharan, Naval Physical and Oceanographic Laboratory, Kochi, India

Line ReversalUsing a PIC16c508 -  Scroll to find this circuit #4- If a device is connected between two output lines as shown in fig: 5, a program can be written so that the device sees a voltage reversal.  When one output is HIGH the other is LOW and this is then reversed.   __ Contact: Colin Mitchell

Linear Circuits for Digital Systems -  Linear Technology AN31 __ Designed by Jim WilliamsFeb 2nd, 1989

Linears for Digital Systems -  AN31 Subtitled "Some Affable Analogs for Digital Devotees, " discusses a number of analog circuits useful in predominantly digital systems.  VPP generators for flash memories receive extensive treatment.  Other examples include a current loop transmitter, dropout detectors, power management circuits, and clocks.  __ Linear Technology/Analog Devices

Litter Box -  PIC Project  Not every new use of technology requires a microcontroller.  This one uses a 12 volt computer fan from CompUSA, a snap close food box from Walmart, some PVC pipe from Home Depot, and a large plastic storage container from Big Lots.   __ Designed by Luhan MonatMesa Arizona

LM3909 LED flasher -  LED flasher with the LM3909 IC and runs from1.5-Volt battery.   __ Designed by Tony van Roon  VA3AVR

Logic ‘High’/’Low’ Indicator -  This logic 'high'/'low' indicator circuit comprises two ICs.  One is hex inverter IC 7404  (IC1) and the other is a bistable multivibrator built around timer IC 555  (IC2) .  A logic probe...__ Electronics Projects for You

Logic analyzer pushes microcontroller to its limit -  12/07/00  EDN-Design Ideas A simple logic-analyzer design is compatible with all versions of Windows and pushes the PIC 18C252 chip to its speed limit to achieve a 1-MHz sampling rate  (Figure 1) .  The circuit can examine three channels of relatively low-speed logic signals that have infrequent, or sparse, transitions.  The analyzer can record only 510 transitions per run, but a run can last as long as several minutes, if necessary.  Applications include monitoring the I/O of an IBM keyboard or printer port, TI-calculator intercommunication, and serial  (RS-232) signals __ Circuit Design by Tom Lyons Fisher, Inexpensive Systems, Huntingdon, PA, and Michael Deskevich, Juniata College, Huntingdon, PA

Logic circuits using discretes -  There have been many times when I've been designing machinery controls where I have needed a logic function but only one so it's not worth using a quad logic gate.  Here are some of the ways I use.  Look carefully at them and you may gain a new perspective on logic and truth tables! __ Designed by Richard Torrens

Logic Family Voltage Translation -  how to translate between TTL, 74xx, CMOS , ECL, PECL, Low Voltage TTL, LVTTL, etc

Logic IC yields simple, wide-range timer -  08/01/97 EDN-Design Ideas You can use a 4060B binary counter/oscillator to make a simple, accurate, long-delay timer.  The circuit offers longer times (milliseconds to hours] than you can achieve with common IC timers.  A positive logic level at the input holds the counters in the reset state and the output in the low state.  When the input goes low, the output goes high, forward-biasing D1 and "stalling" the oscillator __ Circuit Design by Harry Bissell Jr, Robotron Corp, Southfield, MI

Logic offers Complementary Switch Control -  12/06/01 EDN-Design Ideas The complementary-switch controller in Figure 1 uses a few inverter gates to provide drive signals for the complementary switches.  Complementary-switch configurations find wIdeaspread use in synchronous-rectification circuits, charge pumps, full-bridge control circuits, and other circuits.  The circuit in Figure 1 provIdeas not only a complementary drive signal but also a deadtime delay __ Circuit Design by Yen-Hsu Chen, Analog Integrations Corp, Hsinchu, Taiwan

Logic probe -  This logic probe uses a single CMOS IC and shows three logic conditions, High, Low and Pulsing.  In addition if the probe input is neither hi or low  (the high impedance state of tri-output logic IC's) then no LED's will light.    Power from the logic probe is taken from the logic circui __ Designed by Andy Collison

Logic Probe uses Bicolor LED -  03/13/98 EDN Ideas -  (File has several circuits, scroll to this one) A project posed the challenge of replacing existing analog potentiometers  (used to set brightness and contrast levels]in video monitors with digitally controlled potentiometers.  The different brands and models of monitors presented widely varying voltages across the potentiometers.  The design.    __ Circuit Design by Mark Shill, Burr-Brown Corp, Tucson, AZ

Logic PSU with OverVoltage Protection -  A simple 5 Volt regulated PSU featuring overvoltage protection. __ Designed by Andy Collison

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

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