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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.

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:

Network Car Controller -  PIC Project  Our present car controller runs on a single PIC16F870 micro and provides functions for remote door locks, headlight reminder, and car finder.  It is constructed using wire-wrap to allow for future expansion and is mounted using Velcro on the passenger side of the center console __ Designed by Luhan Monat-Mesa Arizona

Network Forms Digital to Impedance Converter -  03/14/96 EDN-Design Ideas The circuit in Figure 1 resembles a capacitive-ladder (C-2C]D/A converter.  However, it does not provide conversion from a digital code to a voltage or current, but rather converts the digital code to a capacitor value.  The C-2C topology is well-suited __ Circuit Design by Alex Belousov, SMP Inc, Rego Park, NY

New approach to video-signal conditioning -  10/08/98 EDN-Design Ideas In digital sync-tip clamping, a stand-alone "clamping" ADC (CADC] incorporates the dc-restore function at its input and eliminates the need for external timing strobes.  This technique encompasses a complete front-end architecture, including sync detection and automatic gain control (AGC] and provIdeas __ Circuit Design by Lazar Shifrin, Advanced Imaging Solutions

New Battery Charger ICs Need No Heat Sinks -  DN124 Design Notes __ Linear Technology/Analog Devices

New ICs Simplify Battery Charging from the USB -  DN320 Design Notes __ Linear Technology/Analog Devices

New MAR-8A & MAR-8ASM Amplifiers -  AN-60-024 Application Note__ MiniCircuits.com

NiCad Charger -  Sometimes its more convenient to recharge batteries 'in place' rather than removing them and putting them in an external charger.  This device is built around a PIC12F675  (a dandy little part from Microchip) .  The number of cells  (1 to 8) is programmed in using the one button __ Designed by Luhan MonatMesa Arizona

Nonvolatile digital potentiometer gates logic signal 09/03/07  EDN-Design Ideas A novel use for digital potentiometers employs them as a logic gate that functions as soon as the system powers up __ Circuit Design by Reinhardt Wagner, Maxim Integrated Products, Ottobrunn, Germany

Off the Shelf MmIC Suits Mixer Applications  -  02/02/98 EDN-Design Ideas You can use a standard monolithic-microwave IC (MMIC) to configure an efficient and economical microwave mixer.  Some systems require a mixer with an input level lower than -10 dBm.  Many available mixers, however, require greater than 10-dBm input power.  The circuit in Figure 1 exploits the inherent nonlinearity of a Mini-Circuits  (Brooklyn, NY) MAR6 microwave amplifier to configure a low-level mixer.  The idea is to add the input signals and feed the sum to the MMIC  (Figure 1a) .  The amplifier's saturation characteristic produces the harmonics and intermodulation products.  The MMIC has greater than 10-dB gain at frequencies over 1 GHz, a desirable characteristic for making mixers for the 0.9, 1.8-, and 2.5-GHz bands. __ Circuit Design by Leira Paz, M Pereira Varela, and FP Fontán, University of Vigo, Spain

Off-The-Shelf ICs Make 10-Bit Convolver -  12/19/96 EDN-Design Ideas The block diagram in Figure 1 shows how you can implement a 333 10-bit kernel using two dual FIR-filter and two delay-buffer ICs.  This configuration operates with clock speeds of 32 MHz.  With the appropriate modifications, the technique is also applicable to convolutions that require greater than 10-bit resolution.  The block diagram implements the 333 convolution as the sum of three row vectors' dot products.  FIR 1A and 1B implement the top two row vector dot products, and dual FIR 2B implements the bottom row vector dot product.  FIR 2A provIdeas a path for summing the three dot products to obtain the convolution sum. __ Circuit Design by Guenter Kremser, Harris Semiconductor, Munich, Germany

Oh no! Not Another CFL Inverter-  Yep another one but this one's really simple.  Its powered from 12V and is just the shot for running multiple compact flourescent lights  (CFLs) or even a small colour TV set.__ SiliconChip

One I/O line drives shift register with strobe -  03/28/13  EDN-Design Ideas This Design Idea shows how a single microcontroller port can drive a lot of output lines through shift register. by Zoran Mijanovic & Nedjeljko Lekic

One microcontroller serves multiple external interrupts -  02/01/01 EDN-Design Ideas In designing µC-based systems, you often face a situation in which the µC has to respond to an external event happening at an uncertain moment in time.  One example is receiving an echo from an object in a pulse-range measuring sy __ Circuit Design by Abel Raynus, Armatron International, Melrose, MA

One switch controls digital potentiometer -  09/19/02  EDN-Design Ideas This design idea     is an evolution and simplification of another  (Figure 1, Reference 1].  Replacing the three inverted-input NOR gates with their logical equivalents, positive-input NAND gates, makes these three gate symbols consistent __ Circuit Design by Jim Bach, Delphi Delco Electronics Systems, Kokomo, IN

One-Of-Nine Switch Position Indicator -  Originally conceived as a track-in-use indicator for model railway layouts, this one-of-nine indicator can used with any selector switch with up to nine positions.  It can be used with a bank of reed switches, as might be used on a locomotive turntable or traverser on a model railway layout or with any switch with up to nine positions.  Then we realised it had many other uses __ SiliconChip

One-Pulse-Per Second Driver for Quartz Clocks -  This simple add-on module for the GPS-Based Frequency Reference is designed to drive the escapement coil of a low-cost quartz clock movement.  It uses the 1Hz GPS pulses available at the rear of the Frequency Reference so that the clock can display local time with GPS-based accuracy.__ SiliconChip

Optimizing LNA Performance for CDMA Application using Nonlinear Simulator 6/24/02  -  App Note  Doc #955__ California Eastern Laboratories

Oscar: Electronic Noughts & Crosses Game -  Noughts and crosses may rate quite poorly amongst young gamers of today but in the late 1960s, a machine, more often called an electronic brain than a computer, playing noughts and crosses against a human opponent, was quite a sensation.__ SiliconChip

Our Best LED Torch Ever! -  It's based on a Luxeon Star/O 1W ultrabright LED, runs off two "D" cells and blasts our previous LED torches into the weeds!__ SiliconChip

PAL colour bar generator -  I started this project 3 weeks ago, because I was wondering " is that possible, some AVR MCU to create simple colour bars? " At the beginning, I  believed that it's easy.  So, I asked some people who knew more about PAL composite video signal.  The first idea was to work with 8.867238 MHz crystal    (2 times the color carrier) .  When I read about PAL video composite signal creation, I saw that if you want to product colors entire-in-software you must create the color-carrier    (4.43 MHz) , changing 4 times the phase of color-carrier    (one time for each color) , to show 4 colours.  Except that, you have to change the color-burst from 135 deg to 135+90= 225 deg. __ Designed by © Vassilis Serasidis

PAL Powers Universal ISA Bus Interface -  02/02/95 EDN-Design Ideas A pc board bearing the 16-bit ISA data-bus interface in Fig 1 can adapt automatically to either 8- or 16-bit motherboard slots.  The interface comprises three bidirectional octal buffers and glue logic.  The glue logic controls transfer direction and output enables __ Circuit Design by Jerzy R/ Chrzaszcz  Institute of Computer Science, Warsaw University of Technology, Nowowiejska, Warsaw, Poland

Parallel Port Microchip PIC Micro Controller Programmer -  PIC Programmer is an essential tool if you wish to learn or build projects with Microchip PIC Micro Processors.  This programmer is built using Free Windows Software called WinPicProg and other similar software from PICALLW or Oshosoft 

Parallel Port PIC Programmer for PIC18F2550 -  Developed specifically for programming of PIC 18F2550 micro controllers, this parallel port, no-power, programmer is the smallest of all programmers ever built.  A DB25 Male Connector, one capacitor and a resistor makes this Port Powered programmer.  Programmer takes its power from Parallel Port pins 2-9.  VPP for this programmer is 5V and hence "LVP" must be selected in programming software.  

Parallel Port PIC Programmer with ICP -  This programmer is built for Free Windows Software called WinPicProg developed by Nigel Goodwin and uses a 74HC14 instead of 74LS05 used on other parallel port programmers.  

Parallel Port Relay Interface -  Below are three examples of controlling a relay from the PC's parallel printer port  (LPT1 or LPT2) .  Figure A shows a solid state relay controlled by one of the parallel port data lines  (D0-D7) using a 300 ohm resistor and 5 volt power source.  The solid state relay will energize when a "0" is written to the data line.  Figure B and C show.   __ Designed by Bill Bowden

Pardy Lights: an Intriguing Colour Display -  OK, so they're really "party" lights.  They're easy to build and produce random colour patterns to the bass beat from your music.__ SiliconChip

Passively Probing an InfiniBand System with an Agilent 16700 Series Logic Analysis SystE - M -  Passively Probing an InfiniBand with Agilent 16700 Series Logic Analysis System.  Agilent App Note 2004-03-05

PC Parallel Port Wizard -  This simple gizmo can test your PC's parallel port.  It can also teach you a lot about the way parallel ports operate.__ SiliconChip

PC Serial Port Receiver CMOS -16 Bit -  This circuit was designed to control a 32 channel Christmas light  show from the PC serial port.  Originally designed with TTL logic,  it has been simplified using CMOS circuits to reduce component  count.  It is a fairly simple, reliable circuit that requires only  4 common CMOS chips    (for 8 outputs) , an optical isolator, and a  few discrete components. __ Designed by Bill Bowden

PC to Die For: Part 2-You Can Build It Yourself -  Partitioning and formatting the hard disk drive, installing the operating system and sqashing the bugs__ SiliconChip

PC-Based Configurable Filter Uses No Digital Potentiometers -  01/23/03 EDN-Design Ideas Fleapower flasher draws less than 50 µAModern instrumentation requires digital control signals.  These signals come from a central microprocessor or, in modern context, the popular parallel or serial PC ports.  In recent times, digital potentiometers have eliminated the hassles from this interface for the analog section.  Designers can replace the resistors of the analog design with digital potentiometers, thus providing the necessary __ Circuit Design by Saurav Gupta and Tejinder Singh, New Delhi, India

PC-Controlled Burglar Alarm SystE - M -  Fancy a full-featured alarm control panel with dialler capabilities? This one is PC-programmed and controlled and can handle up to eight zones.  The PC only needs to be powered up for arming and disarming, or you can use an optional keypad.__ SiliconChip

PC-Controlled Mains Switch -  Build this project and team it with an old PC to control external devices.  It works on anything from a 386 up!__ SiliconChip

PCI Timing Check using the Agilent E2920 PCI Series Exerciser/Analyzer -  Application Note__ Aligent

PC-PIC Serial -  PIC Project  The standard rs-232  (com port) interface specifies +/- 12 volt signals.  It is possible to work quite well with +/- 5 volts.  This circuit works by 'stealing' the negative voltage from the COM port and using it to communicate back.   __ Designed by Luhan MonatMesa Arizona

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

Peltier-Effect Tinnie Cooler -  Its Based on a peltier-effect module fitted with a fan-cooled heatsink.  You just install it in a 6-pack Esky to keep your tinnies cool__ SiliconChip

Perform the XOR/XNOR Function with a Diode Bridge & a Transistor -  05/24/12  EDN-Design Ideas Remember DTL? These discrete DTL-like circuits let you implement the XOR and XNOR operations with a minimum of components.  When designing logic for higher-than-usual supply voltages, such as 24V, you can use a voltage regulator with a standard logic family and interface it through level shifters.  Alternatively, if the logic is not too complex and the speed is not extensively high, you can build gates from discrete components and operate them directly from the available voltage.  Discrete-component AND, OR, and NOT functions are relatively straightforward, but XOR and XNOR functions usually require combining several of the basic AND, OR, and NOT functions.   __ Circuit Design by Raju Baddi, Tata Institute of Fundamental Research, Pune, Indi

Personal Noise Source for Tinnitus Sufferers -  Portable device generates soothing pink or white noise to mask out unwanted sounds.__ 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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