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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

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 Game Show Timer -  Several Game Show timers included, scroll to find this one.  Using only two CMOS IC packages, this game show buzzer performs well enough to be on TV! The first contestant to press his button locks out the other two contestants.  The design is completely asynchronous and "fair".  Other logic families will also work and any appropriate power supply is fine.  For simplicity, a single-chime doorbell is used for the aural indicator.  If a buzzer is preferred, use double pole pushbuttons with the second poles connected to activate the buzzer.  Simply connecting a buzzer in place of the doorbell will work but the buzzer will sound until the reset switch is pushed.   __ Contact: Charles Wenzel of Wenzel Associates, Inc.

Digital Impulse Relay -  In the first place, a relay is like a switch to a coil assembly.  This switch is activated when electricity is applied to the coil.  With a common relay, the electricity must be continuously applied to the coil to __ Designed by Magirescu Iulian

Digital Instrument Display for Cars-Part 1 -  Fancy a digital readout to replace analog gauges? This unit works with a variety of automotive sensors and is dead easy to build.__ SiliconChip

Digital Instrument Display for Cars-Part 2 -  Based on a PIC microcontroller, this simple project lets you convert the analog instruments in your car to a digital display.  It's suitable for use with fuel gauges, oil pressure gauges and temperature gauges, and even features an alarm output.__ SiliconChip

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

Digital LED Clock & Timer -  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

Digital LED Lighting Controller for Chrismas Lights -  It's that time of year again when all those Christmas lighting devotees start planning and building their displays for the festive season.  They might have dozensif not hundredsof different light arrays and they will be thinking about buying even more.  Is this you? Have you thought about controlling lots of your lights in time to music? Well now you can!__ SiliconChip

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

Digital Lighting Controller for Christmas Light Shows, Pt.2 -  Everyone who has seen this has been pretty impressed and no wonder! While we originally intended it to make your Christmas Lights display the best in your suburb, with up to 32 channels and total power limited only by your power outlets, it's capable of controlling just about any lighting sequencing task you want to throw at it.  Now we get on with the good stuff: putting it all together!__ SiliconChip

Digital Lighting Controller for Christmas Light Shows, Pt.3 -  Christmas is just about here! Have you got your Digital Lighting Controller ready yet? In the first two articles we explained how the Digital Lighting Controller works and how to build it.  This third article explains how to use the softwareprimarily the Windows-based sequencing program.__ SiliconChip

Digital Lock -  The Circuit Board is designed to accept 2 types of Drive transistors.  I Used a 2N3906 in this schematic, but for Higher Current Drive for a Solenoid, You can use Various T0-220 PNP types of transistors.  USE ONLY ONE OR THE OTHER, NOT BOTH.  In the Picture, I just put a Resistor and LED, where the Solenoid should go.   __ Designed by G.L. Chemelec

Digital Lock-In Milliohmmeter -  A milliohmmeter is just the tool for checking trace resistance on a printed circuit board, tracking down shorted traces, and measuring the contact resistance of a switch or connector.  Its the kind of tool that would come in real handy occasionally, but not often enough to justify shelling out hundreds of dollars.  Wanting one anyway, I set out to make my own.  It turned out to be not only an exciting project, but a true adventure of discovery as it provided a window into the workings of lock-in amplifiers __ Designed by Dick Cappels

Digital Logic Based 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

Digital 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

Digital Megohm & Leakage Current Meter -  Looking for an electronic megohm and leakage current meter, for quick and easy testing of insulation in wiring and equipment? Here's a new design which allows testing at either 500V or 1000V.  It can measure insulation resistances up to 999MΩ and leakage currents to below 1μA.  It uses a PIC microcontroller and displays the results on a 2-line LCD panel.__ SiliconChip

Digital MEMS Microphone Simple Circuit Interface to a SigmaDSP Audio Codec  -  From this point, follow the documentation for the EVAL-ADAU1761Z regarding software installation, setup, and operation of the system__ Analog Devices from the Lab

Digital noise generator -  When 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

Digital pedometer -  Pedometer has a range of 9.950 meters with2-digits.  Slip it in pants pocket for walking and jogging __ Contact: Flavio Dellepiane, fladello @ tin.it

Digital position encoder does away with ADC -  05/08/97 EDN-Design Ideas The position encoder in Figure 1 is a simple yet powerful circuit that converts the change in resistance of a potentiometer into a digital value without using an expensive A/D converter.  The working principle is a resistance-to-PWM converter built around the common 555 timer IC.  A change in the potentiometer's __ Circuit Design by Jose Carlos Cossio, Santander, Spain

Digital pot adjusts LCD's contrast -  02/04/99 EDN-Design Ideas NOTE : Page includes several designs.  Scroll to find this one.  You can use a digitally controlled potentiometer for many purposes.  In this example, you can use the device to regulate the contrast of a standard (such as two lines by 40 characters] LCD.  You can use the circuit in Figure 1 in a portable test system, in which you need to change the contrast of the LCD as a function of the viewing angle.  You choose the contrast setup __ Circuit Design by Jef Collin, CSE Systems, Turnhout, Belgium

Digital Pot Corrects for System Drift -  EDN-Design Ideas 11/10/94    The circuit in Fig 1 looks simple but usually comes as a revelation to designers.  Under control of the system's P, the digital potentiometer, IC1, becomes a variable set-point reference that can adapt to the long-term drift of the variable measured.  The digital potentiometer replaces schemes involving A/D and D/A converters  (see "Autocalibrator nulls dc offsets," EDN, June 9, 1994, pg 139, and "Infinite-hold circuit zeros out long-term drift," EDN, March 3, 1994, pg 90) .    __ Circuit Design by Mark Rutledge, Xicor Inc, Milpitas, CA

Digital potentiometer autonulls op Amp -  10/22/98 EDN-Design Ideas Op-amp applications that need the highest possible dc accuracy are generally best served by CMOS chopper-stabilized amplifiers, such as the LTC1050.  But high-speed, low-noise applications may require high-performance rockets, such as the 700-MHz LT1226.  So what to do for applications __ Circuit Design by Stephen Woodward, University Of North Carolina, Chapel Hill, NC

Digital Potentiometer Controls LCD Bias -  03/17/94 EDN-Design Ideas Designers of pen-based computers can easily relegate some controls that were previously mechanical, such as switches and potentiometers, to on-screen icons.  For example, the circuit in Fig 1 shows one way that digital logic can control the -24V-dc LCD bias using two general-purpose I/O command lines.  The DS-1669 from Dallas Semiconductor __ Circuit Design by Michael Cortopassi, Dauphin Technology, Lombard, IL

Digital Potentiometer Controls Phase Shift -  02/15/96 EDN-Design Ideas You can use dual, quad, or hex potentiometers to put all phase-shift sections under control of a microprocessor, as in Figure 2.  The DS1806 hex digital .    __ Circuit Design by Rick Downs, Dallas Semiconductor Dallas, TX

Digital potentiometer programs & stabilizes voltage reference -  05/30/02 EDN-Design Ideas The potentiometer portion of a mixed-signal, digitally programmable potentiometer adds variability to an analog circuit, and its digital controls provide programmability.  You can use a digital potentiometer in two ways in an analog circuit.  You can use it as a two-terminal variable resistance, or rheostat, or as a three-terminal resistive divider __ Circuit Design by Chuck Wojslaw, Catalyst Semiconductor, Sunnyvale, CA

Digital potentiometers enable programmable biquadratic filter -  07/22/04 EDN-Design Ideas Of the many types of analog filters available to designers, few allow easy adjustments of the filter parameters.  The biquadratic, or biquad, filter is an exception, however.  You can change that filter's corner frequency (ω0], Q, and gain (H] by adjusting the values of three resistors.  For that purpose, the lowpass biquad circuit of Figure 1 includes three digital potentiometers configure __ Circuit Design by Deborah Mancuso and Donald Schelle, Maxim Integrated Products, Sunnyvale, CA

Digital Potentiometers: Frequently Asked Questions -  App Note/ 593 / Nov-05__ Maxim Integrated

Digital Pulse Generator Project -  Build This Easy Digital Pulse Generator Project to Drive Your TTL & CMOS Integrated Circuits __ Designed by braincambre500 @ yahoo.com

Digital Pulser -  Here is a small digital tester that can be used to test and troubleshoot digital circuitry.  The circuit is essentially a pulse generator activated by a single press-to-on switch  (pushbutton) .  Momentarily...__ Electronics Projects for You

Digital Radar Speedometer -  This circuit is a Digital Radar Speedometer.  It allows us to evaluate the speed of any object moving, especially cars and other vehicles.  The speed is calculated in kilometers per hour  (KPH) .  Its display has three digits.  This radar works with the laser reflexion.  It sends laser radiation to the object and this object reflects the laser radiation.   __ Contact: IQ Technologies

Digital 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.  __ Learning Electronics

Digital RF Field Strength Indicator -  Useful as a transmitter tune-up meter or an RF sniffer, this is an RF field strength indicator that is loosely based on the Broad Band RF Field Strength Probe, described elsewhere.  It detects RF via a square law detector, basically its a crystal set with gain.  The bias circuit for the detector is significantly modified from the probe to reduce the effects of battery voltage droop during use.   __ Designed by Dick Cappels

Digital RF Level & Power Meter -  Need to measure small signals at radio frequencies? Here is a low-cost digital level and power meter which will allow you to measure RF signals from below 50kHz to above 500MHz.  As well as indicating the signal level in volts and dBV, it also shows the corresponding power level  (into 50 ohms) in both milliwatts and dBm.__ SiliconChip

Digital Signal Controls Sine Generator -  05/15/03 EDN-Design Ideas The circuit of Figure 1 produces an accurate, variable-frequency sine wave for use as a general-purpose reference signal.  It includes an eighth-order elliptic, switched-capacitor lowpass filter, IC3, which uses a 100-kHz square-wave clock signal that microcontroller IC2 generates.    (Any other convenient square-wave source is also acceptable __ Circuit Design by Simon Bramble, Maxim Integrated Products, UK

Digital Signal processor DSP for radio communications -  The W9GR DSP-3 is an improved low cost digital signal processor for radio communications use.   It features 18 DSP functions, a LED display, and 13 bit audio precision__ Quantics

Digital signals produce pure sine waves -  10/09/97  EDN-Design Ideas Analog oscillators produce excellent sine waves but are temperamental and hard to design.  They also require extensive redesign every time you change the oscillation frequency.  Digital oscillators.       __ Circuit Design by Ronald Mancini, Harris Semiconductor, Melbourne, FL

Digital Simulation Logic Value Systems -  02/03/97 EDN-Design Feature  In addition to representing logical values, simulators need to represent the strengths of those values.  The problem lies in how a simulator can accomplish this task. __ Circuit Design by Clive "Max" Maxfield, Intergraph Computer Systems

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

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