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Computer Interface Circuits

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Last Updated: December 22, 2017 02:12 PM


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

C-52 Evaluation Board   -  This board uses 89C52 with a modified 8kB PAULMON2 monitor program, 32kB SRAM for writing application program.  The C-52 EVB was designed for studying "Assembly and C Language Programming for Microcontrollers".  Latest PCB file included __ Designed by Wichit Sirichote

C-52 Evb Robot Controller  -  Use a C-52 EVB for simple robot experiments.  Build a simple two wheels robot with L293 H-Bridge driver and IR sensor.  Write a C program controls robot tracked with black tape.   __ Designed by Wichit Sirichote

C52EVB V2.0 with 32KB Eeprom Boot Loader  -  New Microprocesssor Learning Board for 89C52 CPU with 32KB external eeprom.  Modified PAULMON2 provides program saving and boot loading __ Designed by Wichit Sirichote

Calculator using Postfix Notation  -  Doing calculations in a microcontroller-based project is common.  Such calculations done by the microcontroller are pre-written as a part of the code, which means that these formulae cannot be changed or__ Electronics Projects for You

Capacitive Sensor  -  Easily adjustable, high sensitivity circuit; Minimum parts counting __ Contact Flavio Dellepiane, fladello @ tin.it

Capacitor Doubles PLD's Performance  -  09/14/95 EDN Design Ideas:  Troubleshooting interrupts and DMA requests on the iSA bus can be tedious and time-consuming without the appropriate tools.  A digital storage oscilloscope or logic analyzer works well, but LEDs are usually fine for monitoring buffered interrupt- and data-request lines.  According to the iSA bus specifications, a low-to-high transition __ Circuit Design by Jerzy Chrzaszcz, Warsaw University of Technology, Warsaw, Poland

Capturing Images with USB Camera, Wi-Fi & Raspberry Pi  -  Ever since this tiny, credit-card-sized computer, Raspberry Pi, appeared in the market, it has caught the imagination of every electronics and computer hobbyist around the world.  The powerful Linux operating system__ Electronics Projects for You

Cascade ABCD two-port networks  -  12/23/99 EDN Design Ideas:  Telephone subscriber lines have become a topic of intense interest for organizations attempting to transmit internet signals on telephone lines.  Basic loop standards exist, and tables of twisted-pair primary constants extending to 20 MHz are in the literature.  Asymmetric digital-subscriber lines (ADSLs) are now available for high-speed internet service.    __ Circuit Design by Bert Erickson, Thomson Consumer Electronics, Fayetteville, NY

CCD Linear Image Sensor to PC Parallel Interface  -  The CCD Array Reader project began with a free sample of the Texas instruments TC102-1 CCD Linear image Sensor and its rather terse data sheet.  The TC102-1 provides virtually no support circuitry, only the raw CCD (with a few special pixels) and a simple output buffer.  The board shown below was designed to continously scan the TC102-1 and output a stream of digital data in parallel format.  A PC computer displays the data graphically using a simple program __ Designed by Paul Stoffregen

CD ROM Drive as Digital Audio CD Player  -  This circuit converts CD ROM drive in computers into a standalone audio CD player by just connecting power supply options to CD ROM and interconnecting it to either a tape deck or an audio amplifier.   __ Designed by M.P.VERMA

CentronICs Port D/A converters & low-pass filter  -  JDAC and CENT_DAC are both simple Digital to Analogue converter to use with your iBM PC/AT or compatible.  Those circuit are connected to Centronics parallel port and does not affect the normal port usage in any way.  The circuits are transparent to computer, so it is not possible to program to see if those devices are connected or not. __ Designed by Tomi Engdahl

Channel-Link PC B & Interconnect Design-In Guidelines  -  The Channel Link Transmitter’s function is to convert a wide
parallel TTL bus into a smaller faster LVDS interface, and the
Receiver’s function is to recover the data and re-generate the wide TTL bus.  The system block diagram is shown in Figure 1.  Channel Link delivers multiple benefits to Datacom and Telecom applications.  __ Application Note 1108 John Goldie August 1998

Character LCD Displays. Part 1  -  LCD character displays can be found in espresso machines, laser printers, children's toys and maybe even the odd toaster.  The HitachI HD44780 controller has become an industry standard for these types of displays.  This tutorial will__ 

Character LCD Displays. Part 2  -  This tutorial continues from Character LCD Displays - Part 1.  In this part we will connect the LCD module to an Atmega8 microcontroller, then write some code to drive it.  The Circuit Our first task is to build the circuit.  Click to__ 

Cheap Cable Of ASIM's ISP Loader for 89Sxxxx   -  Simple hardware for code programming new series MCU from ATMEL, 89S51, 89S52, 89S53, 89S8252.   __ Designed by Wichit Sirichote

Circuit Adapts Differential Input to Drive Coax  -  05/08/97 EDN Design Ideas:  Uses an HFA1100 or HFA1105 to convert a balanced input signal to a single-ended output signal, uses positive feedback to characteristic-impedance matching while increasing the available output swing, as compared with using a simple series termination resistor __ Circuit Design by Donald Whitney Jr, Harris Semiconductor, Melbourne, FL

Circuit Charges Supercapacitors to 7V from USB Power  -  04/26/07 EDN Design Ideas:  Switching regulator charges three supercapacitors with current limit.    __ Circuit Design by Fran Hoffart, Linear Technology, Milpitas, CA

Circuit compensates system offset of a load-cell-based balance  -  08/16/07  EDN Design Ideas:  A dual DAC stores the system-offset voltage, which gets determined during a power-on calibration sequence.   it’s a challenge to interface a resistive bridge sensor with an ADC receiving its power from a 5V single-supply power source.  Some applications require output-voltage swings from 0V to a full-scale voltage, such as 4.096V, with excellent accuracy.  With most single-supply instrumentation amplifiers, problems arise when the output signal approaches 0V, near the lower output-swing limit of a single-supply instrumentation amp.  A good single-supply instrumentation amp may swing close to single-supply ground but does not reach ground even if it has a true rail-to-rail output. __ Circuit Design by Luca Bruno, ITIS Hensemberger, Monza, Italy

Circuit converts DAC's outputs from single-ended to differential Mode  -  8-Jun-06 EDN-Design ideas This design suits low-end ac applications or high-precision level-setting applications that rely on a single-ended current-output DAC __ Circuit Design by Liam Riordan, Analog Devices, Limerick, Ireland

Circuit Eavesdrops On RS-232C Lines  -  12/05/96 EDN Design Ideas:  When debugging serial links between computers, you need to monitor the data moving in both directions across the serial link.  As long as the data is half-duplex--only one direction "talks" at a time--the circuit in Figure 1can capture data on both the transmit and receive lines of the RS-232C connection and retransmit this data to a third computer.  This third computer can monitor the data using a simple terminal program that allows you to watch the data on a screen and capture the data to a disk file.  The monitoring computer receives but does not transmit information.   __ Circuit Design by Rick Downs, Dallas Semiconductor, Dallas, TX

Circuit Eliminates PC Echoes  -  03/30/00 EDN Design Ideas:  Long-distance-telephone services available via the internet often require the PC user to wear headphones of a headset to prevent echo caused by the microphone’s picking up the loudspeaker outputs.  The circuit in Figure 1 eliminates the echo.   PDF contains multiple circuits, please scroll to find this one __ Circuit Design by Hans Krobath, EEC, Nesconset, NY

Circuit Expands Eight Pin 68hc11 Port to 64 Pins  -  12/07/95 EDN Design Ideas:  The circuit in Figure 1 exploits Strobe B (R/W pin 28) of an M68HC811E2P microcontroller to clock eight 74HC273 latches and thereby expands the output of a single eight-pin port to the equivalent of a 64-pin port.  The circuit uses Port B (pins 9 to 16) , a dedicated output port in the µC, to take advantage of the Strobe B function.    __ Circuit Design by Paul Kemp, NASA Johnson Space Center Houston, TX-- 12/07/95

Circuit for interfacing a relay / solenoid to a PC based on a 2N7000 FET  -  The original computer used on the first servo drive trial table was a hand-me-down that turned out to be a 1995 Cyrix 6x86 133MHz.__  

Circuit for Soft-Start Module  -  Simple circuit that reduces surge current on start of an induction motor __ Designed by Wichit Sirichote

Circuit for UPS to Hybernate PC  -  Most of the low-power UPS systems available in the market do not have the facility to shut down the PC before they turn off automatically due to low battery.  Some of them have the facility but they require software for the same.  __ Electronics Projects for You

Circuit Forms Novel Floating Current Source  -  1-May-03 EDN Design Ideas:  One-shot provide as frequency discrimination - Figure 1 shows a polarization circuit applicable to iSFET (ion-sensitive field-effect-transistor] sensors.  ISFETs are solid-state chemical sensors that measure the pH value of a solution in biomedical and environmental applications, for example.  The circuit in Figure 1 is extremely simple; it sets fixed-bias conditions for iSFET sensors (VDS=i0 RX; iDS=i0] __ Circuit Design by S Casans, AE Navarro, and D Ramirez, University of Valencia, Burjassot, Spain

Circuit forms satellite-dish command Decoder  -  4-Mar-04 EDN Design Ideas:  By decoding the commands sent by a direct-broadcast satellite receiver that uses the DiSEQC (digital-satellite-equipment-control] protocol, you can troubleshoot the commands or simply listen in.  Eutelsat Corp (www.eutelsat.com] offers the DiSEQC protocol.  The technique uses only the coaxial cable between the receiver and the dish to send commands for actions such as changing the low-noise-block __ Circuit Design by Mark Giebler, Oakdale, MN

Circuit Programs EEPROMS  -  01/04/01 EDN Design Ideas:  When you migrate to 3.3 V system supplies, you must usually replace your old, reliable EEPROM programmer with a new, overly flexible and expensive universal programmer.  We could not find a 3.3 V programmer for less than $1000.  For  __ Circuit Design by Jarrod Eliason, Ramtron, Colorado Springs, CO

Circuit Protects Computer's Input  -  05/26/94 EDN Design Ideas:  The circuit in Fig 1 performs input protection, level translation, isolation, and debouncing.  The circuit allowed the output of a relay driver to connect to a computer even though the relay driver delivered a voltage as high as 24V and the relay driver had no ground connection.  With the values in Fig 1 the low and high thresholds at the circuit's __ Circuit Design by Ang Tzu Seng, Halliburton Drilling Systems, Singapore

Circuit provides 4- to 20-mA loop for microcontrollers  -  05/27/04  EDN Design Ideas:  The 4- to 20-mA current loop is ubiquitous in the world of controls in manufacturing plants.  Discrete logic, microprocessors, and microcontrollers easily cover the digital portions of control schemes, such as limit switches, pushbuttons, and signal lights.  Interfacing a 4- to 20-mA output to a rudimentary microcontroller can be problematic __ Circuit Design by Robert Most, Dow Corning Corp, Auburn, MI

Circuit Translates TTY Current Loop to RS-232  -  08/01/98 EDN Design Ideas:  (NOTE: Multiple circuits in this file, scroll to find this one.) The circuit in Figure 1a provide as signal translation between a passive current-loop (TTY) interface and a duplex RS-232C port.  The current flowing in the receiver loop causes the transistor to pull down RxD; when the transistor turns off, R1 pulls up RxD.  In like manner, the current in the transmitter loop switches on for a negative TxD voltage and off for a positive voltage.   __ Circuit Design by Jerzy Chrzaszcz, Warsaw University, Poland

Circuits Sort Out the Highest Voltage  -  11/09/06  EDN Design Ideas:  Greatest-of-three voltage detector drives indicators and external display __ Circuit Design by Ezio Rizzo, Nova SNC, Genoa, Italy, and Vincenzo Pronzato, Felmi SRL, Genoa, Italy

Circuits to computerize your room/house  -  So you've read about my Computerized Room or have seen those nifty home automation products advertised in the back of electronics magazines? Or perhaps someone you know has done something similar.  At any rate, you have decided to try it yourself.  The first thing I will say, however is that it is not cheap.  You will first need a computer, but since your reading this, I assume that you already have that taken care of.  Second, you will have to buy about 20 IC 's and a very expensive iSA experimenters prototyping board.  These boards cost anywhere from $16 to $45, and can be purchased from your local electronics store or from Jameco Electronics (See Where To Get Parts).  They have a fairly wide selection.  Buy the 8 bit version, the 16 bit varsion is not needed for this project. __ Designed by Aaron Cake

Clock Controller V1.1   -  The Clock V1.  1 provides the same function as the saver does but with additional 4-digit LED display and 4-key input for setting the clock and turn on/off AC load.  The circuit uses single 2051 chip, and relay or opto-TRIAC output for driving AC load.    __ Designed by Wichit Sirichote

CMOS inverters convert RF to digital signal  -  01/05/06 EDN Design Ideas:  Hex-inverter-based design suits frequencies up to180 MHz __ Circuit Design by Francis Rodes

Combine two 8-bit outputs to make one 16-bit DAC  -  30-Sep-04 EDN Design Ideas:  inexpensive, 16-bit, monolithic DACs can serve almost all applications.  However, some applications require unconventional approaches.  This design idea design concerns circuitry I recently designed for a tunable-diode laser spectrometer for a Mars-exploration application.  The control circuitry included two 16-bit DACs that interface to the radiation-hardened, 8051-variant 69RH051A microcontroller __ Circuit Design by Steve Woodward, Chapel Hill, NC

Commodore 64 24-Bit Parallel Port Interface with 8255  -  High Quality simple unit.  No need for a Preamplifier __ Designed by Peter Jakab

Commodore Datasette Tape Beeper  -  A while ago at the comp.sys.cbm newsgroup (yes  I'm still typing in 2014, you new-fangled web forumers) , a post was made asking if the schematic was available for the "PET Beeper", a device made in the 70s for the Commodore PET computer. __ Designed by Kevin Koster

Commodore Power Monitor-See if your power supply is frying your '80s computers  -  The Commodore computers of the eighties are growing ever older, yet many continue to enjoy them.  Faulty power supplies can be the cause of instability and failure in all computers, the Commodore Power Monitor plugs into the User Port of the Commodore VIC -20, C64, C128 and Plus4 and warns if the voltages from the external power supply are significantly out of spec.  or contain problematic ripple voltage. __ Designed by Kevin Koster

Commonly Used RS-232 Serial Port Cables  -  This document includes information how to make common wires for RS-232 connections.  I have shown pinouts for standard 25 pin connection and de-facto 9 pin connector used in PCs. __ Designed by Tomi Engdahl

Compact 2-Phase Power Supply Delivers 40a to Intel Mobile CPUs  -  DN284 Design Notes__ Linear Technology/Analog Devices

CompactFlash card to microController with I˛C interface  -  App Note 4418:  This application note explains how to use an i˛C i/O extender to connect a compact-flash (CF) card to the i˛C interface of a microcontroller.  The software commands for reading and writing data are explained.  The MAX7311 i/O port extender is featured in the design circuit.     This Design idea appeared in the September 1, 2006 issue of EDN magazine.   __ Designed by by Fons Janssen, Maxim Integrated Products Inc, Sunnyvale, CA; Edited by Brad Thompson and Fran Granville - September 1, 2007

Compensate system offset of a load-cell-based balance  -  08/16/07  EDN Design Ideas:  A dual DAC stores the system-offset voltage, which gets determined during a power-on calibration sequence.   it’s a challenge to interface a resistive bridge sensor with an ADC receiving its power from a 5V single-supply power source.  Some applications require output-voltage swings from 0V to a full-scale voltage, such as 4.096V, with excellent accuracy.  With most single-supply instrumentation amplifiers, problems arise when the output signal approaches 0V, near the lower output-swing limit of a single-supply instrumentation amp.  A good single-supply instrumentation amp may swing close to single-supply ground but does not reach ground even if it has a true rail-to-rail output. __ Circuit Design by Luca Bruno, ITIS Hensemberger, Monza, Italy

Composite-VGA encoder/decoder eases display upgrade  -  09/28/06 EDN Design Ideas:  Upgrade an RGB video system without adding cables __ Circuit Design by Werner Schwiering, Joystick Scoring Ltd, Whitby, ON, Canada

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Computer Interface:  #'s         A -  B        C -  E
        F -  H        I -  L         M -  P        R  - T       U  - Z


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