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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.

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:


Audible Logic Probe -  Using a conventional logic probe, it is difficult to determine what is happening at a point in a circuit above 50 Hz.  The human eye isnt able to perceive the change...__ Electronics Projects for You

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

Audio Spectrum Monitor -  A digital audio signal processing experiment of real-time FFT    (Fast Fourier Transform) analysis.   __ Designed by The Electronic Lives Manufacturing-presented Chan

Autodim Add-On for the 6-Digit GPS Clock -  Here's a low-cost add-on for the Digital GPS Time Display published in the May & June 2009 issues of SILICON CHIP.  It senses the ambient light level, so that a modified program running in the display unit?s PIC controller can adjust the LED brightness to a comfortable levelranging from full brightness when the ambient light level is high down to dim when the ambient light is very low.__ SiliconChip

Automatic Gain Control AGC -  This project is a digital Automatic Gain Control    (AGC) system using a PIC16F876 MCU.  The ability to set the gain level in a circuit and have it control itself is a very useful function.  This circuit is a building block of another project I am working on.  A 30W power amp for either the PCS, iDEN or CDMA frequency bands.  I will settle on one of those frequencies sometime soon.   __ Designed by steevn.geo @ yahoo.com

Automatic Rain Gauge with Digital Readout -  It collects, measures, records and empties.  Best of all, you don't have to leave the house.__ SiliconChip

Automatic Single-Channel Light Dimmer -  It's fully automatic, has a host of features and will drive incandescent lamp loads up to 2400W.__ SiliconChip

Automatic Single-Channel Light Dimmer-Part 2 -  Second    (and final) article has all the construction and setup details.__ SiliconChip

Automating PC Power-Up -  Tired of pressing the power switch to boot your PC after mains power has been applied? This simple modification does the job for you.__ SiliconChip

Automotive Thermometer -  Keep tabs on in-car temperatures__ SiliconChip

AVR (AT90S2313) composite 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

AVR 2x16 LCD & 4x4 keypad driver -  Connect some 2x16 characters LCD display and 4x4 keypad with AVR microcontroller __ Designed by Vassilis Serasidis

AVR 323 Board -  schematic for an ATMega323 boards    (Mega is pin compatible withAT90S8535) The main interface to this board is RS232

AVR 8 & 20 pin programming adapter  -  Okits not pretty, but its practical.  The 20 pin connector at the far right is left over from a diffferent project and is no longer used.  This adaptor lets me program 8 or 20 pin DIP devices using the In-System Programmer    (ISP) described in Atmel's AVR910 application note.  This circuit provides power and clocks for the part to be programmed and power to the ISP circuit.  When programming 8 pin devices, the part is positioned toward pins 1 and 20 of the socket such that the 8 pins of the chip occupy the pins 1, 2, 3, 4, 17, 18, 19, abd 20 of the programming socket.  In the case of an 8 pin part being programmed, the SPST switch that grounds pin 4 must to be closed.  Conversely, when programming a 20 pint part, the switch on pin 4 must be open so the crystal can be used for the clock for the part being programmed.   __ Designed by Dick Cappels

AVR ATMega8 board for PLL MC145170 -  This board allow to manage a FM transmitter including a Phase Locked Loop    (PLL) on a serial bus    (SPI) like a MC145170.  A current frequency is memorized in EEPROM to configure PLL at power up.  Three auxiliairy frequencies are available for maintenance function and/or HF adjust.  A local interface include 4 keys and a LCD display enable to modify transmitter parameters.  This board can be completely drived from a serial link RS232    (19200 Bds, 8b data, 2b stop, no parity) .  A temperature sensor enable to control working temperature and 2 analog input are used for HF power measure    (Forward and Reflected) .  Information about TOS protection activation is processed by this board to inform user    (local and remote) on a TOS Alarm.  

AVR based oscilloscope -  A mega32 based low speed oscilloscope.  It can be used to measure signals up to 5 kHz.  The input voltage range can be up to 24V AC or 30V DC  __ Designed by Vassilis Serasidis

AVR Based Serial Port IR Receiver -  This is a simple IR receiver circuit which plugs into a serial port of a computer.  Okay, there are many other circuits of this kind, and most of them are even simpler, but this circuit has two major advantages:    (1) it uses an Atmel AVR RISC microcontroller    (an AT90S2313) instead of the usual PIC microcontroller and    (2) it uses a MAX232 for the generation of valid RS232 levels.   __ Designed by Klaus Stock

AVR DDS signal generator V2.0 Part 2. Firmware -  Part 1.  Schematic AVR DDS 2.0 Firmware As I have mentioned DDS function is a modified Jespers DDS algorithm.  Main modification is adding additional ASM line which enables to stop DDS generation.  In version 1.0 the only option was to reset __ Designed by rlocman @ rlocman.ru

AVR DDS signal generator V2.0. Part 1. Schematic -  Finally second and improved AVR DDS signal generator is here.  First AVR DDS V1.0 generator was only an attempt of running DDS algorithm without any amplitude control.  This time I still wanted to keep things simple like minimum count of widely __ Designed by rlocman @ rlocman.ru

AVR Digital Voltmeter -  We build a simple and inexpensive three digit display.  It's a voltmeter module but it has also general purpose digital IO pins.  You could use it as well to read a digital sensor and display the value.  It can be freely programmed, calibrated and even be programmed with a non linear formula.  It's a display where you can define the relation between the measured value and the displayed number.   __ Designed by Guido Socher

AVR Firmware Monitor Program -  Works on AVR controllers with RAM and a hardware UART.  This code is easily modified to integrate with ROM applications to provide the ability to monitor and interact with ROM applications via an terminal simulation program over an RS-232 port.  It can also be used to stimulate and monitor I/O to aid in debugging hardware.  It is very heLPFul to be able to look around at memory, I/O and peripherals, and change things inside a running controller.  If you adapt this to a controller with a stack pointer that is more than 8 bits wide, be sure that both registers in the stack pointer, both spl and sph, are initialized.   __ Designed by Dick Cappels

AVR In-Circuit Programmer -  The programmer is very simple to build.  It contains one IC and a couple of connectors.  As you can see below, with some ingenuity it is possible to squeeze all the circuitry into a DB25 connector shell.  The IC can be a 74HC244 or a 74LS244.  The more normal means of construction is with a small circuit board, with the DB25 connector mounted on one edge, and a header to connect the ribbon cable.  The programmer is designed to work with all the AVR™ family micros, and with the Atmel "ISP" programming software.  

AVR ISP Programmer -  This board can program an AVR microcontroler ATMEL    (ATmega8, ATMega32,) from a parallel printer LPT1 using ISP functionality In System Programming.  This programming type can program and/or configure microcontroler directly on the target board without rmoving device and put it on a separate programmer.  This board is compatible with programming software "PonyProg".  

AVR ISP Programmer (In-Sytem programmer) for ATME - L -  This AVR ISP original by ATMEL you can found on "AVR software and technical Library, April 2003" CD-rom.  It small component count I design new PCB and change some component that easy to build small PCB.  The new firmware was writen by John Samperi for AT90S2313.  This code can program more devices.  

AVR LCD terminal -  The LCD display is represented by the connector X1.  It has a HD44780 compatible LCD controller and I'm using the 4-bit interface to send data to the LCD controller.  The LED's are multiplexed.  I've seen the circuit somewhere in the web.  It is possible to connect 12 LEDs with only 4 tristate ports with this circuit.  You can address the LEDs setting 1 port high, 1 port low and 2 ports to high impedance.  I've only used 8 LEDs because of space problemes in the aperture

AVR LCD Thermometer LM35 -  The LM35 of National Semiconductors that is used in this project is a precision centigrade temperature sensor, which has an analog output voltage.  It has a range of -55C to +150C and a accuracy of 0.5C.  The output voltage is 10mV/C.  The output voltage is converted by the AD convertor of the AT Mega8.  The temperature is displayed on an LCD module.  In this example the thermometer has a range of 0C to 40C and a resolution of 0.5C.  If you want to have a readout in Fahrenheit you can use the LM34.  

AVR Line Following Robot -  Schematic and c source code for building line following robot by Priyank Patil from India.   __ Designed by Wichit Sirichote

AVR microcontroller makes improved Motor controller -  10/17/02 EDN-Design Ideas The circuit in Figure 1 provIdeas a novel method of reading the pulse train using an Atmel   (www.atmel.com] AVR processor, from a typical radio-controlled receiver, and to determine the velocity of a motor.  To capture the pulse train from a typical receiver, you need an external interrupt that triggers based on a rising and a falling edge __ Circuit Design by Anthony Di Tommaso, Cranberry Township, PA, and George Simonoff, Petersburg, OH

AVR PC Stepper Motor Driver -  With this circuit you can control two unipolair stepper motors in full step mode via the RS232 serial port of your PC.  A terminal program such as Hyperterminal can be used to control the stepper motors.  The stepper motors can be driven one at a time.  # Drives two unipolair stepper motors in full step mode # Accepts commands via the serial port of your PC.  # Can be used with any OS that has a standard terminal program such as Hyperterminal.  # Drives stepper motors up to 24V, 500mA # Power supply12-24 VDC.  

AVR PC Thermometer -  With this project you can show the temperature on you PC.  This thermometer plugs on any free serial port.  It gives temperature readings accurate to 0.5C with no calibration.  The project consists of the AVR 2313 Project board and the DS1621 Thermometer board and software for the PC.   

AVR Phone Recorder & Telephony Platform. Part 1 -  This project describes the implementation of a phone line audio and event recorder originally devised for monitoring technical support call center attendants for quality assurance purposes.  Our initial objective was to have a device that digitizes __ Designed by rlocman @ rlocman.ru

AVR Phone Recorder & Telephony Platform. Part 2 -  In the first part we have got acquainted with the device hardware.  Have considered used interfaces and reports and the general principles of work of system.  Device Usage When first turned on, the device tries to initialize the SD/MMC card.  First,  __ Designed by rlocman @ rlocman.ru

AVR Programmer -  To program some AVR microcontroller unit    (MCU) you will need an AVR programmer.  The better way to do that, is to buy some development kit like STK-500.  This kit have the advantage to give you serial port, LCD connector, SRAM socket, 8 switches, 8 LEDs, connectors for all of the ports of MCU and more, to one board.  I suggest to beginners, to start working with STK 500 or some else development system, it will help them very much.  For the people that are want to program only one piece of AVR, to make some circuit from this site and they don't want to spend money for any development kit, the solution is this ultra low-cost AVR programmer.  

AVR Programmer (#268) -  The ATMEL AVR programmer works with the Windows program "Ponyprog" which works under 95, 98, XP, and can be found at http://www.  lancos.  com/prog.  html On board the AVRs that can be programmed are those in the schematic.  For other members of AVR family or the rest programmable ICs that Ponyprog can program, there is the J1 connector    (CON10) which allows expanding the programmer's hardware.  See Ponyprog's site for other's ICs Ponyprog circuits.  The JUMP1 jumper is there to connect the crystal's circuitry to the 8- pin AVRs or to disconnect it.  Some AVRs have internal RC oscillator and an external XTAL is not allowed or needed.  

AVR Programmer (#270) -  The AVR family of `micro-controllers'    (uCs) have their own, non-volatile memory; your program and data are safe, even if all power is lost.  These chips also contain most of what is needed to program them.  If you connect an AVR to the parallel port of a PC loaded with the right software, a `programmer', then PC and uC will happily talk each other through the procedure.  Uploading a program to the chip takes just a few seconds and very little hardware.  It can even be done while the uC is `in-circuit', sitting in the apparatus you want it to control.  A program already in the chip can be erased by the same `programmer'; there is no need for ultra-violet light or a special power supply.  

AVR Programmer (#449) -  This is a ery simple serial ISP progammer for AVR microprocessors.  The schema can be found here.  It is Sample Electronic Programmer compatibile and can be used with Bascom, WinAVR etc.  Previously I used programmer with only 330 ohm resistors in series with MOSI, RESET and SCK.  It worked quite good, but in new version I used buffers to improve separation between LTP and AVR.  In plans full galvanic isolation using optocouplers.  

AVR Programmer-DIY -  This simple AVR Programmer will allow you to painlessly transfer hex program to most ATMEL AVR microcontrollers without sacrificing your budget and time.  It is more reliable than most other simple AVR programmers available out there and can be built in very short amount of time.  

AVR Projects Collection | 20 ATmega MCU Projects -  AVR is a family of microcontrollers developed by Atmel beginning in 1996. These are modified Harvard architecture 8-bit RISC single-chip microcontrollers. ATmega series are one of the types of AVR microcontrollers with features like 4256 KB program memory, 28100-pin package, extended instruction...__ 12/01/2016EFY

AVR Serial Programmer -  Note that the AVR910 programmer does not support all AVR processors, especially the newest chips.  Be sure to check the documentation to see if it supports the version    (s) of the processor you are interested in __ Designed by Dick Cappels

AVR takes under 1s to process quadrature encoder -  EDN-Design Ideas 10/05/2015   A good example of tight interrupt coding to interface to a quadrature encoder.    __ Circuit Design by loan Ciascai & Viman Liviu

AVR Thermometer -  Build a simple digital thermometer using 20-pin uC, AVR 90S2313 and DS1820.  The thermometer is capable of measuring temperature from -55C to +125C! with 1 degreeC resolution.   __ Designed by Wichit Sirichote

AVR Thermometer DS1621 -  This small thermometer board can be connected directly to PORTD of the AVR 2313 Project board.  It uses the Dallas DS1621 Digital Thermometer and Thermostat chip.  The DS1621 measures temperatures from -55 to +125 in 0.5 steps and doesn't need calibration or external components.  It has also a build-in thermostat with high and low set-points which can be programmed by the user.  Below you see the pin description of the DS1621.  

AVR Thermometer TCN75 -  This small thermometer board uses the Microchip TCN75 device.  It is a cheaper clone of the LM75, it costs about 2, 50 Euro.  The TCN75 comes in a SO8 packaging.  The TCN75 is a serially programmable temperature sensor.  It has an output that is programmable as either a simple comparator for thermostat operation or as a temperature event interrupt.  Hysteresis is also programmable.  

AVR Thermometer TCN77 -  The TC77 is a serially accessible digital temperature sensor.  Temperature data is converted from the internal thermal sensing element and made available at anytime as a 13-bit twos compliment digital word.  Communication with the TC77 is accomplished via a SPI and MICROWIRE compatible interface.  It has a 12-bit plus sign temperature resolution of 0.0625C per Least Significant Bit    (LSB) .  The TC77 offers a temperature accuracy of 1.0C    (max.) over the temperature range of +25C to +65C.  When operating, the TC77 consumes only 250 A    (typ.) .  The TC77s Configuration register can be used to activate the low power Shutdown mode, which has a current consumption of only 0.1uA    (typ.) .  

AVR200 Single Board Computer, Pt.2 -  Second article has the assembly details and describes popular software development and programming options__ SiliconChip

AVR-USB Remote Sensor -  Remote Sensor is a wireless thermo- and hygrometer with an USB port on the receiver.  You can draw fancy diagrams of temperature and humidity for up to 16 wireless sensors.

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

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