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

Last Updated on: Monday, October 09, 2017 03:39 PM

Circuits Designed by Dave Johnson, P.E.

If less than 2 circuits, delete ad & merge columns

Audio Frequency 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. . . Circuit by Dave Johnson P.E.-July, 2000

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

Poor Man's TimerOften during testing of certain equipment and components, you would like to keep track of the elapsed time in hours, minutes and seconds.  There are some nice commercial digital timers and counters available for just this sort of application.  However, . . . Hobby Circuit designed by David Johnson P.E.-August, 2008


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

UHF Remote 2-Channel 230VAC Power Switch -  If you're looking for a mains "switch" which can be operated from some distance away, this low-cost, simple project could be just what you want.  With a UHF remote control and two switched "channels", it needs very little power thanks to the use of latching relays.__ SiliconChip

UHF Remote Controlled Mains Switch -  Want to switch mains appliances on and off remotely? This UHF Remote Mains Switch can do it for you.  It's operated using a hand-held UHF transmitter or you can team it with the Water Tank Level Meter Base Station described last month to automatically control mains-operated water pumps.  An in-built timer also enables the unit to turn off automatically after a preset period.__ SiliconChip

UHF Remote Mains Switch Transmitter -  Designed to control the UHF Remote Mains Switch, this hand-held transmitter can operate over a 200m range.  It's based on a PIC micro and a pre-assembled transmitter module, making it easy to build and get going.__ SiliconChip

Ultra LD Mk.2 200W Power Amplifier Module Pt.2 -  Last month, we introduced our new Ultra-LD Mk.2 200W Amplifier module and described the circuit.  This month, we give the assembly details and describe a suitable power supply.__ SiliconChip

Ultra Low Power LCD Indicator -  This circuit serves as an ultra-low power replacement for multiple LED on-off indicators.  It also has the advantage of being easy to read in full daylight.  With the parts shown, it is possible to display four bits of information.   __ Designed by G. Forrest Cook

Ultra Low-Cost Programmer for AT90s Family -  With this programmer you can program AT90S1200,  2313,  2323, 2343, 4414, 4434, 8515, 8535 __ Designed by © Vassilis Serasidis

Ultracompact LCD Backlight Inverters -  AN81 It has become desirable to fashion laptop computers with large area screens, leaving little room for the display's backlight inverter electronics.  Miniaturization limitations of high voltage magnetic transformers impose limits on achievable space reduction.  Another voltage step-up technology, piezoelectric transformers, __ Linear Technology/Analog Devices

Ultra-LD Mk.2 200W Power Amplifier Module -  This new amplifier module supersedes both the Plastic Power module described in the April 1996 issue and the Ultra-LD module presented in the March 2000 issue.  It produces high power at very low distortion.  In fact, as far as we are aware, it is the lowest distortion class-AB amplifier that has ever been published.__ SiliconChip

Ultra-LD Mk.3 135W/Channel Stereo Amplifier, Pt.2 -  Completing the wiring & making adjustments__ SiliconChip

Ultra-LD Mk.3 135W/Channel Stereo Amplifier, Pt.3 -  Finally, we present the specifications for the new Ultra-LD Mk.3 Amplifier along with a couple of minor tweaks to the design to maximise its performance.__ SiliconChip

Ultra-LD Mk.3 135W/Channel Sterio Amplifier, Pt.1 -  Chassis assembly and wiring details__ SiliconChip

Ultra-LD Mk.3 200W Amplifier Module  -  Upgraded design has even lower distortion!__ SiliconChip

Ultra-LD Mk.3 200W Amplifier Module, Pt.2 -  The Ultra-LD Mk.3 amplifier module introduced last month is by far our lowest distortion Class-AB amplifier design.  This month, we present the construction details and give some additional information on its performance.__ SiliconChip

Ultra-LD Mk.3 200W Amplifier Module, Pt.3 -  Power supply & quiescent current adjustment__ SiliconChip

Ultra-LD Stereo Preamplifier & Input Selector, Pt.1 -  Designed for use with the Ultra-LD Mk.3 amplifier modules, this high-quality stereo preamplifier features a motorised volume control potentiometer.  It is teamed with a 3-Input Selector board and both are controlled by the same infrared remote.__ SiliconChip

Ultra-LD Stereo Preamplifier & Input Selector, Pt.2 -  In Pt.2 this month, we describe the assembly of the Input Selector module and its companion Switch Board.  We also show you how to make the IDC cables that link the modules together and give the remote control set-up and test procedure.__ SiliconChip

Ultrasonic Anti-Fouling Unit for Boats, Pt.2 -  In the September issue we published the details of the ultrasonic driver for this project, which is housed in an IP65 case for safety and protection from water ingress.  This month we describe how to encapsulate the ultrasonic transducer so that it is completely safe to handle.  Once it is encapsulated it will operate reliably, even if it is submerged in the bilge of the boat.  We also show a typical installation of the system in a large power boat.__ SiliconChip

Ultrasonic Water Tank Level Gauge -  Do you have a tank to collect rainwater? Do you know how much water is in it? This ultrasonic tank level gauge fires an energy burst which bounces off the surface of the water ? and then a microcontroller calculates how far down the tank water level is.  Clever, eh!__ SiliconChip

Under Sampling Extends utility of Digital Scopes -  04/09/98 EDN-Design Ideas -  (Several circuits included, scroll the find this one)  By undersampling the input signal, you can use a digital oscilloscope to digitize and display or collect signal data of even RF and IF signals.  To sample a signal without aliasing, you must use a sampling rate that satisfies the relationship __ Circuit Design by Robert J Inkol, Defence Research Establishment, Ottawa, ON, Canada

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

Universal High-Energy Electronic Ignition SystE - M -  It works with a variety of trigger inputs and uses a PIC microcontroller to control the switching transistor__ SiliconChip

Universal High-Energy LED Lighting SystE - M -  Incredibly versatile LED lighting system uses a rechargeable battery pack and has lots of applications.__ SiliconChip

Universal I/O Board with USB Interface -  This hardware I/O board will let you drive a host of digital and analog I/O    (input/outputs) via the USB interface on your laptop or desktop computer.  Based on an Atmel Atmega32 microprocessor and not much else, it works on Windows, Linux and Macs.__ SiliconChip

Universal OS PIC Programmer -  This programmer requires only a basic terminal program capable of uploading an ascii PIC HEX file.  It does not matter what operating system or computer  (MAC, Win98, XP, Vista, DOS, Linux, etc.) is used to talk to it.   __ Designed by Luhan MonatMesa Arizona

Universal Voltage Regulator Board -  Digital/Analog USB Data Logger, Pt.3__ SiliconChip

Unused Port Adds a PWM/Analog Channel to a Microcontroller -  8-Oct-09 EDN-Design Ideas Take advantage of unused pins to generate a PWM signal and then filter it into analog __ Circuit Design by Vishwas Vaidya, Tata Motors Ltd, Pune, India

Up / Down Digital Counter with 7 Segment LED Displays -  REVISED   Really as Simple as you can get and has 4 Displays __ Designed by G.L. Chemelec

Updating the PIC Programmer & Checkerboard -  Here's how to use it with Windows 2000/XP and PCs running faster than 1GHz.__ SiliconChip

UPG2301TQ Application Information 8/1/04  -  App Note  Doc #958__ California Eastern Laboratories

Upgraded Software for the EPROM Programmer -  It fixes the bugs and can be downloaded from our website.__ SiliconChip

Upgrading an Ultra-LD Mk.2 Amplifier to Mk.3 Standard -  This teensy PCB lets you add the vital modifications to an Ultra-LD Mk.2 amplifier to bring it up to Mk.3 performance.  We are doing this so that all those people who built the Ultra-LD Mk.2 from the August-September 2008 issues will not be too annoyed with us for superseding it with the Mk.3 version.  After all, we want to keep our readers happy and content!__ SiliconChip

USB Clock with LCD Readout, Pt.1 -  This LCD USB Clock connects to your PC's USB port.  It synchronises its time with your PCand ultimately an internet time serverwhen your PC is on to maintain accurate time-keeping.  It can also operate on its own using battery back-up and has user-selectable display modes.__ SiliconChip

USB Clock with LCD Readout, Pt.2 -  Last month, we detailed the circuit of the USB Clock and showed you how to build it.  This month, we detail the software installation and describe how it is used.  We also describe how to synchronise your PC to an internet time server and how to synchronise the USB Clock to the PC each time the PC boots up.__ SiliconChip

USB digital I/O extender using a PIC18F14K50 -  Add general purpose input/output lines to your computer based or openwrt projects! You can control 12 digital input/output lines from USB port using this circuit.  Each line can be individually set to an input or output, and each output pin can be set HIGH or LOW independently, without changing other output pin states.   __ Designed by Peter Jakab

USB Power Injector for External Hard Drives -  A portable USB hard drive is a great way to back up data but what if your USB ports are unable to supply enough "juice" to power the drive? A modified version of the SILICON CHIP USB Power Injector is the answer.__ SiliconChip

USB Printer Share Switch -  This simple device allows two computers to share a single USB printer or some other USB device, such as an external flash drive, memory card reader or scanner.  A rotary switch selects the PC that you wish to use with the USB device, while two LEDs indicate the selected PC.__ SiliconChip

USB Stereo Recording & Playback Interface -  Now you can use your laptop PC to make high-quality stereo audio recordings with professional standard balanced microphones.  This interface unit lets you make recordings at sampling rates up to 48 kilosamples/second and provides high-quality stereo analog line outputs for playback or monitoring.  There's also an S/PDIF digital audio input for recording and an S/PDIF digital audio output for playback.__ SiliconChip

USB Test Instrument Interface for PCs -  With this USB interface you can turn your desktop or laptop PC into a whole suite of test instrumentsa 2-channel digital scope, spectrum analyser, AC DMM and frequency counter plus a 2-channel audio signal/function/arbitrary waveform generator.  Interested? Read on.__ SiliconChip

USB-Controlled Power Switch -  Build this and automatically power up all your PC's peripherals when you start the computer.  It works via the PC's USB port.__ SiliconChip

USB-Sensing Mains Power Switch -  Do you have to manually switch your PC's peripherals on  (and later off again) each time you boot your PC? If so, this project will make life a lot easier.  It monitors your PC's USB port and automatically turns all that other gear on and off as required.__ SiliconChip

Use a Printer Port to Record Digital Waveforms -  06/18/98 EDN-Design Ideas -  (File includes several circuitsscroll to find this one)  To record or capture special waveforms, those that appear once or have no fixed frequency, the usual technique is to use a logic analyzer or a storage oscilloscope.  However, these tools are very expensive.  Moreover, because of limited memory, a storage scope can record fewer than 1000 samples.  The technique presented here provIdeas an alternative method to recording digital waveforms.  The idea is to use the PC's printer port to sample waveforms, and the PC's memory to store data.   __ Circuit Design by Dean Shen, Dycam Inc, Chatsworth, CA 

Use Eight Timers with PIC16Fxxx Microcontrollers -  18-Feb-10 EDN-Design Ideas Timers debounce switches and let you decide when lapses have expired __ Circuit Design by Luis G Uribe C, Caracas, Venezuela

Use the MCLR Pin as an Output with PIC Microcontrollers -  10-Jan-08 EDN-Design Ideas Adding a MOSFET to a 6-pin microcontroller transforms its reset/programming pin into an output pin __ Circuit Design by Antonio Muñoz, Laboratorios Avanzados de Investigación, Huesca, Spain, and Pilar Molina, Universidad de Zaragoza, Zaragoza, Spain

Uses & Advantages of MERA Dual Matched MMIC Amplifiers -  AN-60032 Application Note__ MiniCircuits.com

Using a Wideband O2Sensor In Your Car, Pt.1 -  This Wideband Controller is intended to be used with a Bosch Wideband LSU4.2 oxygen sensor and our Wideband Sensor Display to accurately measure air/fuel ratios over a wide range from rich to lean.  It can be used for precise engine tuning and can be a permanent installation in the car or a temporary connection to the tailpipe of the exhaust.__ SiliconChip

Using a Wideband O2Sensor In Your Car, Pt.2 -  Last month, we introduced our new Wideband Oxygen Sensor Controller and described the circuit.  This month, we show you how to build it and give the test and installation details.__ SiliconChip

Using Offsets to Avoid False Triggers -  Application Note__ Aligent

Using the AT89C4051 as a RTC (Real-Time Clock) -  If you are looking for the simplest project, you are at the right place.  Its a digial clock which make use of AT89C4051 to work as a Real time clock.   __ Designed by Ajay Bhargav ajay_bhargav @ hotmail.com

Using the Catalog Specifications to Determine MMIC Reliability -  AN-60-030 Application Note__ MiniCircuits.com

Using the Valve Preamp in a hifi systE - M -  Here's how to add a volume control and modify the November 2003 Valve Audio Preamplifier for use with line level signals.__ 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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