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

Last Updated on: Saturday, December 30, 2017 02:17 PM

Circuits Designed by Dave Johnson, P.E.

Digital Counter using PedometerThere are many occasions when you may want to count something electronically.  Perhaps it is car traffic on a street or items moving down an assembly line.  It might be the number of times a machine is activated or maybe you want to count the number of . . . Hobby Circuit designed by David A. Johnson P.E.-August, 2008

Digital noise generatorWhen you need to test an audio circuit with broadband noise, this circuit works great.  It uses just three inexpensive C-MOS ICs that generate a series of output pulses whose widths vary randomly.  I included a level control pot . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2000

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

Digital volume control -  The Tiny Audio Amplifier kit is a good choice for battery operation.  It is based on LM386 IC.

Digital volume control has log taper -  04/11/02 EDN-Design Ideas Digital potentiometers provide a compact and convenient way to attenuate audio-amplifier signals.  However, most such potentiometers suffer from at least one flaw  a nonlogarithmic step increment.  To avoid this problem, a user must usually step the potentiometer in a nonlinear sequence to simulate a logarithmic taper __ Circuit Design by Doug Farrar, Los Altos, CA

Digital Volume Control using DS1669 Digital Pot IC -  This digital volume control has no pot to wear out and introduces almost no noise in the circuit.  Instead, the volume is controlled by pressing UP and DOWN buttons.  This simple circuit would be a great touch to any home audio project.   __ Designed by Aaron Cake

Digital Wattmeter, measures from nanowatts to kilowatts using AD8307, PIC16F876, LCD Display -  The extra input B is for a later SWR brigde project, also the TX serial output will be in use later.  The uncalibrated signal response is: +1/-1 dB from 1MHz to 450MHz.  Input SWR vill varry from 1.00 to 1.30, depending on input frequency.  To make the SWR this good, you need to assemble the input circuit correct and adjust the capasitor.  Input power range: -60 to +30dBm that is 1 nW to 1 Watt.  __ Thomas Scherrer OZ2CPU

Digital waveform generator provides flexible frequency tuning for sensor measurement -  17-Dec-04 EDN-Design Ideas Variable-resistance sensors convert a fixed dc excitation voltage or current into a current or voltage that's a straightforward function of the quantity undergoing measurement.  In another class of sensors, moving objects or fluids produce a sensor signal by altering an LC circuit's inductance or capacitance __ Circuit Design by Colm Slattery, Analog Devices, Limerick, Ireland

Digital wireless for the bench top ATtiny12 -  This section describes an experimental low power, low bandwidth data signaling system that was initially made to operate at 55 MHz  (television channel 2 in the U.  S.) .  Before operating a radio transmitter, find out what kind of transmitter operation, if any, is permitted in your locality.  Radio transmitter operation is a serious legal matter.  This design __ Designed by Dick Cappels

Digital/Analog USB Data Logger -  Based on a PIC micro, this simple project can log lots of data to a memory card.  It can read from many types of digital and analog sensors and features a real-time clock and calendar to "time-stamp" the data.  It has a USB port and comes with a PC host program, allowing you to configure the sensors, change settings and charge the battery.__ SiliconChip

Digital/Analog USB Data Logger, Pt.2 -  Last month, we described the main features of the USB Data Logger and gave the circuit details.  This month, we give the assembly procedure, explain how to install the Windows driver and PC host software and describe how the unit is used.__ SiliconChip

Digital/Analog USB Data Logger, Pt.3 -  In this third and final article on the USB Data Logger, we describe how to use the accompanying Windows host software.  This software allows you to edit and test scripts, upload them to the logger and change its settings.__ SiliconChip

Digital-I/O adapts to many interface voltages -  03/01/07 EDN-Design Ideas Control newer logic families that can't tolerate 5V __ Circuit Design by Steve Hageman, Windsor, CA

Digitally Addressable DALI Dimming Ballast -  A digitally addressable digital dimming ballast has been developed.  It conforms to DALI standard requiring very few parts and operates at very low power.  Applications include building management or studio lighting where it is desired to control single or groups of lamps for conserving energy, performing lamp maintenance or creating prefect light quality.  The design includes the digital dimming ballast, the code of the micro-controller and a platform to control the ballast by PC.   __ Designed by Cecilia Contenti and Tom Ribarich Applications Engineer, International Rectifier, Lighting Group

Digitally Control Gain over a ±40 DB Range -  09/12/97 EDN-Design Ideas Digitally controlled amplifiers typically take the form of programmable-gain amplifiers  (PGAs) .  Though useful for many applications, PGAs have the disadvantage of large, discrete gain steps, such as gains of 1, 2, 4, and 8.  For higher resolution gain steps, you must use a different approach.  The circuit in Figure 1 can digitally control an amplifier's gain over a ±40-dB range.  The circuit has a programmable-gain resolution of 1.25 dB and can attenuate or amplify the input signal, depending on the digital code you apply.  You could use this high-resolution PGA as the front end of an ADC and thus obtain increased dynamic range.  The circuit is also useful as a digitally controlled audio preamplifier.    __ Circuit Design by Mark Shill, Burr-Brown Corp, Tucson AZ

Digitally Control Room Light Intensity -  11-Nov-04 EDN-Design Ideas Many people favor different light and temperature settings for different rooms depending upon their mood or whether they are working or relaxing.  The circuit in Figure 1 controls the intensity of the artificial light in a room and  __ Circuit Design by Donal McNamara and Kieran Kelly, Analog Devices, Limerick, Ireland

Digitally Controlled Phase Shift using the DS1669 -  App Note/ 975 / Dec-05__ Maxim Integrated

Digitally controlled potentiometer sets cutoff frequency -  06/10/99 EDN-Design Ideas The traditional method of controlling the upper cutoff frequency in the basic inverting-amplifier circuit of Figure 1 is to add capacitor C in parallel with R2.  The value of C controls the cutoff frequency.  R1  and R2 independently establish the magnitude of the circuit gain, which __ Circuit Design by Chuck Wojslaw, Xicor Inc, Milpitas, CA

Digitally Programmable Instrumentation Amplifier Offers Autozeroing -  10/30/08 EDN-Design Ideas The current trend in advanced instrumentation amps is to use no external resistors.  In these amplifiers, a gain-control word, comprising a binary-coded one, sets the voltage gain.  Several integer gains within one to 1000 are currently available; however, this range does not __ Circuit Design by Marián Štofka, Slovak University of Technology, Bratislava, Slovakia

Digitally programmable resistor serves as test loA - D -  03/03/05  EDN-Design Ideas Figure 1 illustrates a digitally programmable precision resistance that can serve as a microprocessor-driven power-supply load in custom-designed ATE  (automatic-test equipment].  An 8-bit current-output DAC, IC1, a DAC08, drives curre __ Circuit Design by Francesc Casanellas, Aiguafreda, Spain

Digitally Programmable-Gain Amplifier Uses Divergent-Exponential Curve -  01/08/09  EDN-Design Ideas The divergent-exponential and negative time constants are the core concepts of the DENT  (differential-divergent-exponential-negative-time-constant] digitally programmable-gain-amplifier topology __ Circuit Design by W Stephen Woodward, Chapel Hill, NC

Dimming DALI Ballast for 32w/T8 110V Input -  This reference design is a high efficiency, high power factor, digital dimming electronic ballast designed to drive rapid start fluorescent lamp types.  The design contains an active power factor correction circuit for universal voltage input as well as a ballast control circuit using the IR21592.  The design also includes a PIC16F628 microcontroller and an isolation circuit for connecting to a Digitally Addressable Lighting Interface  (DALI) .  

Dimming DALI Ballast for 36w/T8 220V Input -  This reference design is a high efficiency, high power factor, digital dimming electronic ballast designed to drive rapid start fluorescent lamp types.  The design contains an active power factor correction circuit for universal voltage input as well as a ballast control circuit using the IR21592.  The design also includes a PIC16F628 microcontroller and an isolation circuit for connecting to a Digitally Addressable Lighting Interface  (DALI) .  

Dinsmore 1490 Digital Compass -  Biking in the winter, or at night, is dangerous without a front light.  A good front-light is essential, not only for being seen, but to see the road.  LED lamps will not illuminate the road, and they can be too dim for cars to see you  (1W or better LEDs are quite nice as headlamps.) I offer here a simple  (but high-quality) design to build your own 5 or 10W halogen lamp, which runs off of a rechargeable 7.2V or 7.4V Lithium Ion battery pack. __ Designed by © 2007-2014 Images SI, Inc

Discrete component logic -  I often use discrete component implementations of logic gates in my projects, often consisting of AND and OR gates made from diodes and resistors.  I "invented" or "discovered" how to make these gates when I was about 14 and have been happily using them ever since __ Designed by Hans Summers

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

DIY Terminal Strips -  PIC Project   __ Designed by Luhan MonatMesa Arizona

Door Camera Mount -  PIC Project  If your front door has one of the peep hole viewers, you can use this method to mount a small video camera in its place.  A small project box outside contains the video camera  ($25 from Circuit Specialists) .  The camera is hard to see in this picture; it is in the top half of the box.  A hole just below the center is fitted with a short piece of lamp threaded rod  (from your local hardware store) , a big washer, and the matching nut.  The metal cover for the box is replaced by some 0.060 lexan and held with 4 screws.   __ Designed by Luhan MonatMesa Arizona

Dorji 433MHz Wireless Data Modules -  Chinese 434MHz ISM data modules just keep getting better and better!__ SiliconChip

Dr Video Mk.2: an Even Better Video Stabiliser -  Clean up those copy projection "nasties" and get a rock-solid picture from your DVD player or VCR.__ SiliconChip

Dr Video-An Easy to Build Video Stabiliser -  Clean up those copy protection nasties and get a rock solid picture on your TV from tape or DVD.__ SiliconChip

Dremel drill speed controller -  The Dremel drill fitted with a mini drill-chuck on a stand is a great setup for drilling circuit boards.  The problem is that it does not do low speeds very well.  My unit had a failed internal speed controller, so I just wired around it and connected it to a regulated 24 volt DC supply.  This worked OK, but I would like a slower speed when drilling boards.  slowing down with a lower voltage, however, causes it to stall out completly when it begins drilling.  What I needed was a circuit to actually increase power to the motor under increasing load.   __ Designed by Luhan Monat-Mesa Arizona

Driving Dot LED -  A basic circuit of the 89C2051 shown here can be made easily using point-to-point soldering with a universal PCB.  Use an ordinary 20-pin socket, do not use a circle-pin socket.  D1 is a small dot LED.  U2 can be either 7805 or 78L05.  U3 is optional for correcting any polarity DC adapter.  Without the 2051 chip __ Designed by Wichit Sirichote

Driving LEDs In Parallel & Series using a PIC16c509 -  Scroll to find this circuit #6If a number of LEDs are required to be driven from a single output, you will need to connect them in parallel or series.  There are limitations, however, as you will see.  Firstly it is ok to connect two LEDs in series, provided you work out the value of the dropper resistor.   __ Contact: Colin Mitchell

Driving LEDs using a PIC16c509 -  Scroll to find this circuit #5Each output line of a '508A can only deliver about 25mA.  This current is determined by the size of the transistor delivering the current.  The transistor inside the chip is only very tiny and if a higher current is drawn, it may be damaged.   __ Contact: Colin Mitchell

Driving Light & Accessory Protector for Cars -  External devices on cars are an easy target for thieves.  Or at least they were: this will keep the crooks away from your car.__ SiliconChip

Driving More Than 4 LEDs using a PIC16c509 -  Scroll to find this Circuit #7 -If more than 4 LEDs are required to be driven, a buffer transistor will be required as shown in fig: 12.  This transistor will allow the LEDs to be driven from a 12v supply  (or higher) and the number of LEDs can be increased to 6 per column for 12v __ Contact: Colin Mitchell

Driving VFDs with a PIC -  Vacuum fluorescent displays, known as VFDs  (because both vaccuum and fluoroscent are hard to spell) are commonly used in VCRs and microwaves.  They are relatively bright and have a low power consumption.  Some older calculators used them before LCDs became popular.  Having obtained a few Futaba VFDs from a surplus dealer, I went about trying to interface it to a PIC.  A plea went out on the PIC list and was soon answered by Kalle Pihlajasaari with a few details on VFDs.  

DS1621 PC thermometer -  This incredibly simple thermometer plugs on any free serial port.  Does not make use of any programmable components as microcontrollers.  It gives temperature readings accurate to 0.5°C with no calibration.  It's cheap, so I've put one on any PC I use.  And it is so nice to have the temperature shown on the Windows taskbar, that a million friends asked me to build one.   __ Contact: IQ Technologies

DS1669 Digital Potentiometer -  The DS1669 Dallastat™ is a single digital rheostat or potentiometer with access to all three potentiometer terminals.  The potentiometer has 64 wiper positions with equal or linear resistive step sizes.  This device has both positive and negative 8V  (max) supply inputs for maximum wiper outputs__ Maxim Integrated

DS18S20 1-Wire Digital Thermometer -  The DS18S20 digital thermometer provides 9-bit Celsius temperature measurements and has an alarm function with nonvolatile user-programmable upper and lower trigger points.  The DS18S20 communicates over a 1-Wire bus that by definition requires only

Dual DC Motor speed control with reverse -  I built this way back in 2000 to power a remote control "tank" I built in high school.  Circuit schematic, source code, and pictures of the project are all shown.   __ Contact: Paul Wilkins

Dual Polarity Amplifier has Digital Control -  09/12/96 EDN-Design Ideas The circuit in Figure 1 can amplify a signal either in an inverting or a noninverting mode.  When switch S1 is on and S2 is off, the circuit behaves as a regular inverting amplifier.  When S2 is on and S1 is off, the circuit feeds the signal to the noninverting input of the op amp; thus, the circuit behaves as a noninverting amplifier.  If S1 and S2 are monolithic analog switches, you __ Circuit Design by Rick Downs, Dallas Semiconductor Corp, Dallas, TX

Dual Stepper Motor Driver for a Robot Differential Drive -  This article describes the hardware and the software used to control two stepper motors suitable for a robot differential drive.  The circuit accepts two 2-bit words that command each of the motors to go forward, backward, hold a position, or to idle.  It also provides an output signal when a step is being taken.  It is a flexible design allowing for unipolar and bipolar motors __ Designed by J. L.  John Girard

Dual-Tracking ±19V Power Supply, Pt.1 -  This linear bench supply can deliver up to 1.6A from positive and negative outputs with a range of ?0-19V.  It has adjustable current limiting for both outputs and can display the voltage or current reading for either rail.  If powered from an AC plugpack, no mains wiring is required, although less current is available.  It also has a 5V 750mA output for powering digital logic ICs and microcontrollers.__ SiliconChip

Dual-Tracking ±19V Power Supply, Pt.2 -  Last month, we introduced our new Dual Tracking ?19V Power Supply and explained how it works.  This month, we show you how to build the PC boards, install them in a case, wire it up and get it going.  Both the mains-powered and plugpack-powered versions are covered.__ 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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