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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:

Magnetic Card Reader -  The unit provides the magnetic head on a spring mechanism along with low level head signal amplifiers and data slicers.  Three signal lines coming from the unit provide card presence, clock, and data.  When actively reading a card, it draws about 50ma of current at 5 volts.   __ Designed by Luhan MonatMesa Arizona

Mains Clock Controller using AT89C2051 -  The Clock Controller V1.1was designed to be an exemplary of using 'C' language to control timer0interrupt, 7-segment LED and keypad scanning.  It provides 1-bit sink currentdriving output, for driving a relay, opto-TRIAC, say.  Many projects requiring7-segment display and keypad interfacing may get the idea from the Clockcircuit and software.   __ Designed by Wichit Sirichote

Mains Moderator: Stepping Down the Volts -  Do you have excessive mains voltage at your place? In some parts of Australia the mains voltage can be above 250VAC and that can spell early death for imported appliances rated to work on only 220VAC.  In this article we show you how to reduce the mains voltage to a safe level for your equipment.__ SiliconChip

Mains Voltage Indicator -  This is a circuit for a digital mains voltage indicator that displays main voltage in the form of a LED bar graph with 16 LEDs.  The first LED indicates voltage level at 50 V and the 16th LED shows voltage level for 280 V__ Electronics Projects for You

Maintain precise timing with PC's speaker logic -  07/11/02 EDN-Design Ideas Precise timing control is paramount in data acquisition and analysis and especially in digital-signal processing.  The easiest way of maintaining timing control in a PC is to use delay loops.  The disadvantage of this implementation is that the delay loop's elapsed time depends on the system's operating frequency __ Circuit Design by DS Oberoi, CEDTI, and Harinder Dhingra, GCET, Jammu, India

Make a DAC with a microcontroller's PWM timer -  09/05/02 EDN-Design Ideas Many embedded-microcontroller applications require generation of analog signals.  An integrated or stand-alone DAC fills the role.  However, you can often use PWM signals for generating the required analog signals.  You can use PWM signals to create both dc and ac analog signals.  This design idea shows how to use a PWM timer to simultaneously create a sinusoid, a ramp, and a dc voltage __ Circuit Design by Mike Mitchell, Texas Instruments Inc

Make noise with a PIC -  7-Aug-03 EDN-Design Ideas Building a stable noise generator for audio-frequency purposes requires only a few components.  The circuit in Figure 1 relies on linear-feedback shift registers and some simple software.  An eight-pin Microchip (www.microchip.com] PIC12C508 controller (IC2] with a short program generates pseudorandom noise at its output pin, GP0 __ Circuit Design by Peter Guettler, APS Software Engineering GmbH, Cologne, Germany

Making Boards -  It is now rather easy to make your own single-sided printed circuit boards at home.  The total cost runs about 25 cents per square inchboard, chemicals, and all.   __ Designed by Luhan MonatMesa Arizona

MarshmalLow Bazooka -  This device uses a PIC12F615 to implement a capacitor discharge ignition system.  When the switch  (button) is closed, the PIC sends pulses to the IRF644 MOSFET creating high voltage pulses to charge the 1.0 uf/250 volt capacitor.   __ Designed by Luhan Monat-Mesa Arizona

Max-038 Signal -  The Max-80 function gernerator IC is specified to work to 20 MHz.  So far, this unit works nicely to 50KHz.  Since I seldom need signals higher than that, it has taken up a happy.)  __ Designed by Luhan MonatMesa Arizona

Measure humidity & temperature on one TTL line -  08/30/01 EDN-Design Ideas By combining the responses of an Analog Devices (www.analog.com] AD590 temperature sensor and a Humirel (www.humirel.com] HS1101 humidity sensor, you can generate a single TTL-level signal containing information from both sensors (Figure 1) .  This design uses a 74HC123 monostable multivibrator, IC1, to form a free-running oscillator __ Circuit Design by Shyam Tiwari, Sensors Technology Pvt Ltd, Gwalior, India

Measure Motor Speed Uses Low-Cost Components -  11/08/07  EDN-Design Ideas A microcontroller-based circuit provIdeas both an LCD readout and an analog motor-speed output __ Circuit Design by R García-Gil, J Castelló, and JM Espí, Escola Tčcnica Superior d’Enginyeria, University of Valencia, Spain

Measuring Characteristic Impedance of Short Rambus Motherboard Traces & Small-Outline RIMMs -  Application Note__ Aligent

Memory Card Reader -  SD memory cards, especially the ones under 1GB are cheap, relatively easy to interface and provide vast amounts of memory for imbedded control.   __ Designed by Luhan Monat-Mesa Arizona

Memory termination IC balances charges on series capacitors -  08/18/05  EDN-Design Ideas Get the best performance from high-value capacitors with simple IC circuit __ Circuit Design by Clayton B Grantham, National Semiconductor, Tucson, AZ

Methods Link ECL & PECL -  03/02/95 EDN-Design Ideas The circuit in Fig 1 is one way to link ECL to positive ECL  (PECL) .  So far, no dedicated level-shifting ICs are available for these purposes.   Because the circuits in Fig 1 are ac-coupled, you cannot use them for discontinuous data.  If the inputs go quiet or are pulled high or low, the devices' differential inputs float, possibly resulting in self-oscillation. __ Circuit Design by Cleon Petty and Gary Tharalson, Motorola Semiconductor, Logic IC Division, Mesa, AZ

Micro Spy with FETs -  Circuit and notes only, no circuit description given.   __ Designed by Tony van Roon  VA3AVR

Micro Spy with TTL -  This circuit is old  (70's) but since the 74LS13 is from the regular 74xx series and easy to obtain, I decided to keep the circuit in place until components are no longer available.  Not much to tell here.  Performance is based on the 74LS13, a 'Dual 4-input Positive-Nand Schmitt Trigger'.  This circuit was experimental and so has no real purpose other than tinkering.   __ Designed by Tony van Roon  VA3AVR

Micro Spy with USW -  Circuit and notes only, no circuit description given.   __ Designed by Tony van Roon  VA3AVR

Microbric Viper-The Sumo Module -  Time for a little ROBOT WARS fun!__ SiliconChip

Microchip PIC14 -  Engineers of my generation in the UK will remember the Science of Cambridge Mk14.  Intended to be Sir Clive Sinclair’s first home computer kit for the general public, it served to train a generation of electronics engineers in how to program microprocessors.  The Mk14 was based on, and virtually identical to, the ‘Introkit’ that was available in America at around the same time.  It had a 512 byte monitor ROM, 256 bytes of RAM, an eight or nine digit LED display with bubble magnifiers, and a notoriously bad twenty key keyboard.   __ Contact: Karen's Microprocessor Projects

Microcontroller becomes multifunctional -  10/25/01 EDN-Design Ideas A microcontroller, by default, can execute only one program at a time.  What do you do if, in a given project, you need to performthan one operation at a time? Addmicrocontrollers to the design? In certain cases it's unnecessary.  Consider a real-life situation (Figure 1) .  The microcontroller constantly generates on its Pulse output pin a sequence of pulses with 25-msec duration __ Circuit Design by Abel Raynus, Armatron International, Melrose, MA

Microcontroller Controls Analog Phase Shifter -  06/12/08  EDN-Design Ideas By using a digital potentiometer in a phase-shift circuit, a microcontroller can precisely control phase shift __ Circuit Design by Nick Ierfino, IGS Technologies, Montreal, PQ, Canada

Microcontroller controls multichemistry battery charger -  09/28/00 EDN-Design Ideas Figure 1 is a generalized block diagram of a multichemistry battery charger.  A COP8ACC5 µC handles its key charging features.  The µC is available in a 20-pin (15 I/O pins] SOIC or a 28-pin (23 I/O pins] SOIC/DIP.  It contains 4 kbits of internal ROM.  The controller's A/D inputs monitor __ Circuit Design by Kelly Flaherty, National Semiconductor, Santa Clara, CA

Microcontroller Detects Pulses -  24-Jul-08 EDN-Design Ideas A microcontroller detects output pulses in a device under test __ Circuit Design by Abel Raynus, Armatron International, Malden, MA

Microcontroller Directs Supply Sequencing & Control -  29-May-03 EDN-Design Ideas Obtain higher voltage from a buck regulatorWith the proliferation of dual-voltage architectures and multiprocessor boards, even simple applications can require several processor voltage rails.  With each processor having its own power-up and -down requirements, power-rail sequencing and control can become a complex task.  The challenge for power-supply designers is to consider each processor's timing and voltage requirements and assimilat __ Circuit Design by Joe DiBartolomeo, Texas Instruments, Dallas, TX

Microcontroller discerns addresses in RS-485 systems -  11/08/01 EDN-Design Ideas One of the many benefits of using the RS-485 data-interface system, unlike the RS-232 system, is its ability to implement multidrop networks.  Such networks usually carry 9-bit data words, in which the ninth (parity] bit identifies each word as address or data.  When using small microcontrollers without a hardware UART, such as IC1 in Figure 1, designers must decide whether to add an exte __ Circuit Design by Nigel Brooke and Ted Salazar, Maxim Integrated Products, Sunnyvale, CA

Microcontroller Displays Multiple Chart or Oscilloscope Timing Ticks -  05/01/08  EDN-Design Ideas A crystal controlled microcontroller generates precise timing ticks __ Circuit Design by William Grill, Honeywell, Lenexa, KS

Microcontroller drives 20 LEDs -  09/27/07  EDN-Design Ideas Details and demonstrates the use of "Charlieplexing" to drive 20 LEDs using six available I/O pins on an 8-pin microcontroller __ Circuit Design by Dhananjay V Gadre of the Netaji Subhas Institute of Technology in New Delhi, India

Microcontroller drives H bridge to power a permanent-magnet DC Motor -  15-Mar-07 EDN-Design Ideas Improved H-bridge requires only two driver signals __ Circuit Design by Luca Bruno, ITIS Hensemberger Monza, Lissone, Italy

Microcontroller Drives LCD with Just One Wire -  3-Dec-07 EDN-Design Ideas A Microchip PIC10F family microcontroller sparks an HD44780 LCD using a single I/O pin __ Circuit Design by Noureddine Benabadji, University of Sciences and Technology, Oran, Algeria

Microcontroller drives logarithmic/linear dot/bar 20-LED display -  01/18/07  EDN-Design Ideas Do-it-yourself analog-to-LM3914 display driver offers user programmability __ Circuit Design by Dhananjay V Gadre and Anurag Chugh, Netaji Subhas Institute of Technology, New Delhi, India

Microcontroller emulates numerically controlled oscillator -  02/21/02 EDN-Design Ideas Microcontrollers commonly add intelligence or digital functions to products, but they can also provide a variety of analog signals.  An 18-pin PIC 16C54 microcontroller, combined with an inexpensive, 8-bit DAC and a simple lowpass filter, can generate sine waves from dc to approximately 50 kHz with a tuning resolution of 24 bits __ Circuit Design by Tom Napier, North Wales, PA

Microcontroller functions as voltmeter -  10-May-07 EDN-Design Ideas PIC microcontroller and FETs enable a four-digit voltmeter __ Circuit Design by Noureddine Benabadji, University of Sciences and Technology, Oran, Algeria

Microcontroller Inputs Parallel Data using One Pin -  2-Oct-08 EDN-Design Ideas Clever use of pulses of various time constants allows a microcontroller to input a slowly changing serial pulse stream using a single I/O pin __ Circuit Design by Rex Niven, Forty Trout Electronics, Eltham, Victoria, Australia

Microcontroller makes effective frequency counter -  11/23/00 EDN-Design Ideas Figure 1 shows an efficient and costeffective frequency counter using an Atmel 89C2051 mC (Reference 1) .  The design can use any mC of the 8051 family.  The circuit counts frequency and sends the count to a PC via the serial portPDF has several circuits, scroll down to find this one __ Circuit Design by Fazal Pathan, Physical Research Laboratory, Ahmedabad, India

Microcontroller Measures Resistance Without an ADC -  112/05/08 EDN-Design Ideas By configuring the I/O ports of a microcontroller as an astable multivibrator, you can measure the resistance of a resistive sensor __ Circuit Design by Ashish Aggarwal, Netaji Subash Institute of Technology, Dwarka, India

Microcontroller Moving-Dot Display Interface Uses Three I/O Lines -  05/01/08  EDN-Design Ideas A moving-dot LED-display interface to a microcontroller uses only three output pins __ Circuit Design by Abel Raynus, Armatron International, Malden, MA

Microcontroller multiplexes DIP switches to I/O port -  02/17/00 EDN-Design Ideas At times, aµC must read a large number of DIP switches, such as for system identification, bus-address setup, manual configuration, or other purposes.  However, the available number of I/O lines is sometimes not enough to assign a switch to each one.    __ Circuit Design by Gregory Willson

Microcontroller multiplexes six digital potentiometers -  05/11/00 EDN-Design Ideas In Figure 1's circuit, a µC lets you adjust as many as six digital potentiometers.  Like mechanical potentiometers, digital potentiometers can adjust regulator outputs or speaker volumes and act as rheostats.  Available in resistances of 50, 100, and 200 kV, they let you throw away your mechanical potentiometers and the little flat-headed screwdrivers that go with them.   __ Circuit Design by Ted Salazar, Maxim Integrated Products, Sunnyvale, CA

Microcontroller or DSP Controls On/Off Function -  13-Nov-03 EDN-Design Ideas In many applications, a single on/off button switches the power supply on or off.  Usually, the system switches off regardless of the processing function or workload the microcontroller or DSP circuit is currently handling.  The small circuit in Figure 1 is intended to make the microcontroller or DSP circuit the master over this on/off function __ Circuit Design by Dirk Gehrke, Texas Instruments, Freising, Germany, and Frans Ravn, ChemoMetec A/S, Alleroed, Denmark

Microcontroller Produces Analog Output -  16-Oct-03 EDN-Design Ideas A brushless dc motor needs several voltage levels to control its speed  0V to stop the motor, 5V to run it at maximum speed, and some voltages between these extremes to run it slower.  When you use such a motor in a system under microcontroller supervision, the microcontroller should generate all these voltages __ Circuit Design by Abel Raynus, Armatron International, Melrose, MA

Microcontroller programmer taps power from PC’s serial port -  04/26/07  EDN-Design Ideas A PC's serial port can supply enough power to supply a microcontroller programmer __ Circuit Design by GY Xu, XuMicro, Houston, TX

Microcontroller Provides an Alternative to DDS -  7-Jan-10 EDN-Design Ideas Use a microcontroller to generate the codes for a DAC __ Circuit Design by Daniele Danieli, Eurocom-Pro, Venice, Italy

Microcontroller provides low-cost analog-to-digital conversion, drives seven-segment displays -  10-May-07 EDN-Design Ideas Versatile conversion circuit detects and displays signal's peak value __ Circuit Design by Name withheld by author’s request

Microcontroller provides SRAM battery backup -  26-Jun-03 EDN-Design Ideas To maintain content in the event of power loss, many designs that include SRAM require a dedicated device that can automatically switch from a standard power supply to battery operation.  Microcontrollers seldom find use in power-switching applications.  Because microcontrollers typically operate from the primary power supply, they stop execution if that supply drops, thereby making it impossible __ Circuit Design by Dave Bordui, Cypress Semiconductor, Orlando, FL

Microcontroller provides timer function -  01/04/01 EDN-Design Ideas The circuit in Figure 1 is a µC-based programmable timer with two output channels.  The first channel, activated by pressing the red switch, S3, has a red LED at its output.  This channel is active until it reaches its desired time-out point.  The second output channel connects to a green LED __ Circuit Design by Tito Smailagich, ENIC, Belgrade, Yugoslavia

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

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