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Computer Interfaces Circuits

µC Reprograms Audio DAC Via Serial Interface: 01/07/99 EDN-Design Ideas / PDF contains multiple circuits - scroll to find this circuit.

10 Base T Solutions Network Interface Adapter: National Semiconductor Application Notes,28 Jun1996

12Bit ADC Interface:

18 bit ADC uses PC's serial port: 09/27/2001 EDN - Design Ideas /  A PC usually requires a plug-in ADC card to process analog signals. However, with the circuitry in Figure 1, a PC can communicate with an 18-bit ADC through its serial port. The port provides both positive and negative power supplies as well as control signals. IC1 is an 18-bit MAX132 ADC with a serial interface.

2 Channel, Port Powered RS232 to RS 422 Converter: information on commercial product, datasheet includes full circuit diagram  

2 Transistor Circuit Replaces IC #1: 02/07/02 EDN-Design Ideas  / Jim Hagermans article  Linear Technologys recently introduced LTC4300 chip buffers I2C clock and data lines to and from a hot-swappable card. This task is difficult because the IC must work bidirectionally.

2 Transistor Circuit Replaces IC #2:  02/07/02 EDN-Design Ideas  / Linear Technologys recently introduced LTC4300 chip buffers I2C clock and data lines to and from a hot-swappable card. This task is difficult because the IC must work bidirectionally.

24 Bit Parallel Port Interface With 8255 for Commodore Computer:

24 Line Parallel Interface for the PC :

4 Channel 8 Bit Analog to Digital Converter for PC:

8254 Timer & Counter Board:

9 to 9 Pin (Female) Null Modem Cable:

AC Switching With TrIAC From TTL:

ADCx RS232 Interface Schematic:

Add CAD functions to Microsoft Office: 03/21/2002  EDN - Design Ideas / Microsoft Word has excellent drawing capabilities. You could use it effectively to perform some CAD tasks, such as schematic entry. Word is by far the most popular text processor on the market, and it would seem desirable for technical writers to be able to create a single integrated document file combining both text and graphics in an editable format. .

Add current boost to a USB charger: 09/19/2002  EDN - Design Ideas / The popular USB interface can charge a portable device while transferring data. But for high-capacity batteries, the 500-mA output current of USB hosts and powered hubs greatly extends the charging time. (Unpowered USB hubs supply no more than 100 mA.) Thus, a system that accepts charging power from an ac adapter as well as the USB port is more convenient..

Add Speech Encoding/Decoding to your Design: 02/04/99 EDN-Design Ideas  / PDF contains multiple circuits - scroll to find circuit.

Add voice command to virtual instrumentation: 05/30/2002  EDN - Design Ideas / Debates still persist in the engineering community about the relative merits of analog and digital controls of instrumentation. Meanwhile, a revolutionary new type of control—voice-command control—is gaining acceptance in many application areas (Reference 1). This Design Idea focuses on the practical implementation of the Voice Commander voice-command interface in a virtual-instrume....

Add voice commands to your CAD system: 05/02/2002  EDN - Design Ideas / The first time I activated the Language Bar (Speech Tools) in my Microsoft Word 2002 and started dictating this Design Idea, the on-screen title displayed "cat" instead of "CAD." By using the "Add/Delete Words" feature, I've trained the system to recognize the "CAD" acronym. This was my first experience with the MOSR (Microsoft Office Speech Recognition) tool, which is part of the latest Micros....

Adding Second joystick to PC joystick Interface:

Analog Signal Acquisition for PC Printer Port:

AVR DMX 512 Dongle for PC's: simple interface between DMX-512 equipments and personal computer that is connected to computer parallel port, can transmit256 channels and receive128 channels DMX data simultaneously

AVR microcontroller makes improved motor controller: 10/17/2002  EDN - Design Ideas / The circuit in Figure 1 provides 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..

Build Logic Gates using Discrete Parts:

Build your own joysticks:

Casio Organizer Interface:

CCD Video Capture Camera Circuit on Request:

Centronics Port DA Converters & Lowpass Filter:

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 Eavesdrops on RS232C Lines: 12/05/96 EDN-Design Ideas 

Circuit Protects Computer's Input: 05/26/94 EDN-Design Ideas 

Circuit Translates TTY Current Loop to RS232C: 08/03/98 EDN Design Ideas  / Provides signal translation between a passive current-loop (TTY) interface and a duplex RS-232C ports

Commonly used RS232 Serial Port Cables:

Computer Controlled Model Train Set:

Computer Microphone: adapting electret microphone to soundcards with dynamic microphone inputs  

Computerize your Room / Home:

Computerized Infrared Remote: control your stereo, TV and VCR from Windows, includes schematic and software  

Connect other Circuits to PC joystick Port:

Connect Two CD ROM Drives to One Soundcard:

Connecting Sega 3D Glasses to a PC Serial Port:

Control 120VAC Relay With TTL:

Convert Atari Style Joystick to PC Joystick Port:

Convert Ataristyle joystick to PC joystick Port:

Convert Hauppauge Infrared Remote Control to IRMAN: How to modify Hauppauge Infrared remote control receiver to work as IRMAN compatible remote control receiver. The text is in Finnish.  

Data Bus Monitor:

Data Transmission Lines & Their Characteristics: National Semiconductor Application Notes,05 Oct1998 

Decoder Safely Drives Data Bus Buffer: 07/18/96  EDN-Design Ideas 

Design a visible optical link for RS 232C communications: 01/09/03  EDN-Design Ideas / The design in Figure 1 is a visible optical link for those who need to see the transmitted data. An isolation figure of more than 5000V is a bonus. Tests of the system used the COM input of a data-acquisition system, as well as a standard PC's COM port. The MC1489 converts the RS-232C data to TTL signals...

Differential to Single Ended Converter: 03/14/96 EDN-Design Ideas 

Digital to Analog Centronics D / a & Filter:

Disco Lights: software and hardware for controlling disco lights from your PC  

Drawing Power From a PC Serial Port: This circuits derives fairly low power, (mA at5V) from a RS-232 serial connection. (NOTE: ASCII drawing) 

Drive Local Interconnect Network With PCType UART Device : 04/15/02 Electronic Design - Ideas for Design / A new single-wire serial communication system, called the Local Interconnect Network (LIN), is intended for electronic control units in vehicles (www.lin-subbus.org). Using a PC UART for LIN provides a convenient and low-cost solution for...  

Driving a N Channel FET From TTL: Meant as a quick n easy example of how to switch high current12V dc from TTL.  

Driving a Relay With a CPU:

Electrical Equipment Control using PC:

Embedded processor directly drives LCD: 01/09/03  EDN-Design Ideas / Driving a bare LCD does not necessarily require specialized interface circuitry or peripherals. This Design Idea describes an alternative drive scheme, which you can easily implement using the general-purpose outputs of a microcontroller. Many embedded-system applications need to interact with a user by displaying simple numeric or alphanumeric character…

Emissions killers Trap Common Mode Currents: 03/03/98 EDN-Design Ideas  / Unshielded twisted-pair cable that is transformer-coupled to a digital system can easily act as a radiating antenna because of common-mode currents induced by unwanted stray coupling from the digital portions of the system

Encoder and PC make complete motor control system: 12/12/2002  EDN - Design Ideas / This Design Idea combines a simple ISA-bus-resident interface circuit; a garden-variety PC; a high-resolution optical shaft encoder; and a PWM-controlled, 0.05-hp, brushed, permanent-magnet dc motor to make a high-precision and high-power motion-control system. The system sequences the precise rotation of an evacuated steel bell jar several feet in diameter, such as those used in molecular-beam....

Encrypted routines impede hackers, protect licenses: 04/04/2002  EDN - Design Ideas / The use of public-key-encrypted algorithms within licensed applications can prevent hackers from cracking the licensed algorithms. Moreover, you can use them to disable licensed features that a user doesn't purchase. Licensing schemes eventually arrive at some critical decision point at which an algorithm decides whether the user is entitled to run that application.

Envelope follower combines fast response, low ripple: 12/26/2002  EDN - Design Ideas / Envelope followers extract amplitude information from complex audio waveforms. The resulting dc voltage often drives nonlinear stages, such as voltage-controlled amplifiers or filters. You must make a careful trade-off between the speed of response to a rapidly changing input signal and the amount of ripple in the dc output that you can tolerate..

Envelope Tracker quells jitter: 07/07/94 EDN-Design Ideas

EPROM Emulator:

EPROM Prog / Emul PSU:

EPROM Programmer Mk1:

EPROM Programmer Mk2:

Ethernet / Cheapernet Physical Layer Made Easy With DP8391 / 92: National Semiconductor Application Notes,04 Nov1995

Excel Formula Calculates Standard 1%Resistor Values : 01/21/02 Electronic Design - Ideas for Design / The Excel cell formula below calculates the nearest standard 1%-resistor value without using a lookup table or macro. Type or electronically paste the text below into any cell (other than A1). The formula will calculate the nearest 1%-resistor for the...  

Fake Joystick Circuit: This simple circuit can be used to make the computer to think that there is a real joystick connected to joystick port. This adapter might be useful in some special computer testing applications when you dont have real joystick available.  ASCII drawing. 

Fax to Modem Interface:

Filtering PC Bus Power:

Four Channel 8 Bit Analog to Digital Converter for PC:

Frame Grabber W /  Parallel Port Interface:

GameBoy Camera Parallel Port Interface:

General Purpose 48 Bit ISParallel I / O Card:

Get Power Out of PC Parallel Port: An article which includes circuits, shares how to us a parallel port to connect to a very wide selection of devices like software protection dongles, removable disks, modems, network adapters, printer sharing units, parallel port extenders, soundcards, electronic telecard readers and many circuits. 

Getting Power From Serial Port:

Group Delay Equalizer has Gain More than One: 10/12/95 EDN-Design Ideas 

Hints and kinks for USB decoding: 02/07/2002  EDN - Design Ideas / The USB is a serial data-transmission system that uses cables to connect peripheral equipment to PCs. All new computers have two or more USB receptacles, and the predictions are that they will replace most of the legacy receptacles on older PCs. The 1.0 and 1.1 standards for USB were for 1.5 and 12 Mbps at low- and full-speed rates, respectively.

How to get Power From PC to your Circuits:

Hyperbaric FallTime Viscometer Is PCBased : 10/28/02 Electronic Design - Ideas for Design / The measurement of the viscosity of solutions is an integral element in analytical chemistry and chemical manufacturing. It has particular value in designing and controlling the processes of polymerization, an essential step in the production of...  

IC Adds Full Duplex RS485 Operation: 11/23/94 EDN-Design Ideas  / Simple RS-485 repeater provides full-duplex communications with only tow ICs

IDE hard Disk Interface for Amiga 500:

Infrared Computer Controlled Infrared Device:

Infrared Interface With Windows CD Software: use infrared technology to remotely control a CD-ROM drive with an audio CD  

Infrared Remote Control Of your PC Is Easy!: simple device that connected to the computer serial-port enables the reception of infrared codes emitted from any commercial remote control unit and with a little Windows program the computer learns to recognize sequences and simulates key pressing or executes a program  

Infrared Remote Control Repeater:

Infrared Remote Home Control: software Remocon Con for Windows98 able to fire remote control signal through built in infrared port (IrDA) that is of notebook personal computer standard equipment  

Interface 20Bit SigmaDelta ADCs Through a PC's Parallel Port : 03/04/02 Electronic Design - Ideas for Design / In most sigma-delta analog-to-digital converter (ADC) applications, the serial data transfer occurs through a serial port. A microcontroller configures the serial port as required

Interface a serial 12 bit ADC to a PC: 07/10/03  EDN-Design Ideas / Over the years, IC manufacturers have devised various ways of effecting interfaces and paying special attention to reducing the number of ICs' interface-I/O pins. The MAX187 is one such device, a 12-bit A/D converter. You can create an interface to this ADC using serial data communications techniques....

Interface Connects ISBus to µP: 10/09/97 EDN-Design Ideas 

Interfacing 16x2 Character: LCD to parallel port

Interfacing Microphones to Computer Sound Cards:

IS48 I / O Digital Card: ComInt was designed and built for a colleague at work. He needed a device with a large number of I/Os to control his Gameboy device from the PC. A simple circuit using only4 ICs proved to be a good solution. It uses two 8255 Programmable Peripheral Interface chips and provides48 I/O signals, each being software programmable.

ISBus Provides Access to Serial Peripherals: 02/17/97  EDN-Design Ideas 

Isolated Full Duplex RS232C Interface:

Isolated RS232 for PIC16F84:

Joystick Interface Projects:

Joystick Interfaces: analogue interfaces for joysticks for motor controllers 

Joystick Port As General Purpose Input:

Key Reading Circuit Saves I/O Pins: 03/06/03 EDN-Design Ideas / PDF contains multiple circuits - scroll to find this circuit

LAN Switch Eliminates Redundant PHY Chip: 03/31/03 Electronic Design - Ideas for Design / Advances in notebook technology create a thirst for new features and increased functionality, culminating in greater cost and shrinking space. One solution to the cost/space issues is to use a wide-bandwidth analog local-area network (LAN) switch that...

Laptop Computer Serial Port Power Booster:

Line Driver Economically Synthesizes Impedance: 01/06/94 EDN-Design Ideas  / Line-driver circuit uses a second op amp to synthesize the output impedance rather than inserting a power-hungry resistor in series with the op amps output

Linux Infrared Remote Control (LIRC):

Lookup Table Facilitates Bit Flipping: 11/23/00 EDN-Design Ideas / PDF contains multiple circuits - scroll to find this circuit.

Low Power Ethernet With the CMOS DP83910 Serial Network Interface: National Semiconductor Application Notes,05 Aug1995

Low Power RS232C Driver & Receiver in CMOS: National Semiconductor Application Notes,05 Oct1998

Low Voltage Powers ParallelPort Interface : 06/24/02 Electronic Design - Ideas for Design / For portable-sensing and data- acquisition applications, a laptop computer and its parallel port (LPT) make good bedfellows. Yet in the effort to extend battery life, many microprocessors and entire systems operate with logic levels down to 1.8 V. The...  

Mains Manager:

Maintain precise timing with PC's speaker logic: 07/11/2002  EDN - Design Ideas / Precise timing control is paramount in data acquisition and analysis and especially in digital-signal processing. The easiest way of maintaining timing control in a PC is to use delay loops. The disadvantage of this implementation is that the delay loop's elapsed time depends on the system's operating frequency

Make Eight Channel Measurements through An LPT Port: 06/13/02 EDN-Design Ideas / The circuit represents a simple and cost-effective way to obtain eight-channel analog-signal acquisition through a PCs LPT port. IC1, a12-bit, serial-output MAX187 ADC, operates from a single5V supply and accepts analog inputs of0 to5V.

Make eight channel measurements through an LPT port: 06/13/2002  EDN - Design Ideas / The circuit in Figure 1 represents a simple and cost-effective way to obtain eight-channel analog-signal acquisition through a PC's LPT port. IC1, a 12-bit, serial-output MAX187 ADC, operates from a single 5V supply and accepts analog inputs of 0 to 5V. IC2, an eight-channel MAX338 analog multiplexer, also operates from a single 5V supply..

Microcontroller Interface for 5KW Microwave oven:

Microprocessor RS232 Reset:

MIDI Controlled Switches: can drive up to128 individual relays, solenoids, motors, etc. with a MIDI note-on and note-off messages  

More Accurate PC / AT Clock: Nixie Tube Clock 

NES to Atari 2600 Controller Interface:

Novel idea implements low cost keyboard: 04/03/03  EDN-Design Ideas / Many applications that use a microcontroller also use a keyboard. If your application uses a relatively powerful microcontroller, you can use several free I/O pins or an unused input with an ADC to effect an easy keyboard connection. But, if the microcontroller in your system has too few free I/O pins and no on-chip ADC, you can be in trouble...

Null Printer Adapters:

Parallel Port Central: information on using PC parallel port for I/O and Windows drivers for that, useful for your own circuit interfacing  

Parallel port controls arbitrary waveform generator: 06/13/2002  EDN - Design Ideas /  You can use the parallel port of your PC and a few additional components to generate a powerful, easy-to-use arbitrary-waveform generator. By using a Visual Basic program with the circuit in Figure 1, you can generate any waveform (for example, sinusoid, triangle, amplitude- or frequency-modulated, or exponential decay) by simply entering its characteristic equation..

Parallel port provides high resolution temperature sensing: 10/03/2002  EDN - Design Ideas /  High-resolution temperature sensing at low cost is possible using only one chip attached to the PC's parallel port (Figure 1). The Dallas Semiconductor (www.dalsemi.com) DS1722 digital thermometer allows measurement resolution as fine as 0.0625°C in digital form and with linear response. The accuracy specification is only 2°C, but you can improve this figure by careful calibration..

PBUS, Multi Drop RS422 / 485 type Ne2 Rk for Interconnecting PIC Nodes:

PC / XS Transfer: (PDF) A circuit and C code for bidirectional transfer of data between an XS40 Board and a PC.

PC and LongBaseline Chronography Measure Ballistic Parameters Acoustically : 07/22/02 Electronic Design - Ideas for Design  / Ballistics is an ancient art

PC Based 7 Segment Rolling Display:

PC Based Biofeedback Monitor:

PC based configurable filter uses no digital potentiometers: 01/23/03  EDN-Design Ideas / Modern 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 .....

PC Based Configurable Filter uses No Digital Potentiometers: 01/23/03 EDN-Design Ideas  / PDF contains multiple circuits - scroll to find this circuit -- Modern 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.

PC Based Digital Storage Oscilloscope (DSOA):

PC Based Digital Storage Oscilloscope Mk3:

PC Based EFI Programmer:

PC Based Lighting Control: short pointer to each of the available commercial PC based lighting console systems  

PC Based Lighting Control: short pointer to each of the available commercial PC based lighting console systems

PC Based Oscilloscope:

PC board layout eases high speed transmission: 11/08/2001 EDN - Design Ideas / As digital techniques move to higher speeds, designers become aware of the need to treat pc-board traces as RF transmission lines. In these lines, you strive to hold the line impedance, Z0, to a constant value-typically, 50U-and to terminate the line with the same impedance. Data families such as ECL, PECL, and LVDS send data over a pair of traces known as a balanced tra... .

PC configurable RLC resonator yields single output filter : 08/07/03  EDN-Design Ideas / This Design Idea presents a versatile filter circuit for low-power-consumption instrumentation that you can program from your PC using the parallel port. The circuit uses analog switches and latches instead of digital potentiometers for the digital control (figures 1 and 2). By running simple software code on the PC, you can configure a single robust design to work as a lowpass, highpass, or b......

PC Controlled Current Source Supplies 100V, 1A, 16Bit Pulses : 04/29/02 Electronic Design - Ideas for Design / The current source shown in the figure is designed to support toroidal-cavity nuclear-magnetic-resonance electrophoresis (TCNMRE) measurements of molecular electrical mobility in chemical samples. To do so,...  

PC Controls inexpensive Waveform Generator: 06/05/96 EDN-Design Ideas

PC Controls Light Dimmer: 08/19/99 EDN-Design Ideas / Circuit design idea from EDN Magazine to control one light dimming from PC

PC hardware Monitor Reports the Weather: 01/18/01 EDN-Design Ideas  / PDF contains multiple circuits - scroll to find the one of interest   -

PC Infrared Remote Control #1:

PC Infrared Remote Control #1:

PC IR Remote Control:

PC Monitors twoway RS232 Transmission: 02/01/01 EDN-Design Ideas / PDF contains multiple circuits - scroll to find this circuit.

PC Mouse Implementation using CoP800: National Semiconductor Application Notes first published05-Aug-1995

PC Mouse Implementation using CoP800: National Semiconductor Application Notes first published05-Aug-1995

PC Parallel Port Output Capabilities: includes instructions how to connect a relay to PC parallel port  

PC Smart