Computer Circuit

Quick view of Data recieving from printer Port LTP1

The diagram below shows 5 switches connected to the 5 input lines of the parallel port. An external 5 volt power supply is used to provide high logic levels to the input pins when the switches are open. Three 1.5 volt batteries in series can be used to obtain 4.5 volts which is close enough. The 330 ohm resistors in series with the port connections provide some protection in case a connection is made to the wrong pin. If you are sure of the connections, the 330 ohm resistors can be left out and the switches connected directly to the input pins. The negative side of the power supply should be connected to the ground point, or any pin from 18 to 25. ..

RS232 reciever schematic

RS232 reciever schematic

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. The schematic diagram (SERIAL.GIF) illustrates the circuit with 16 outputs which can be expanded with additional 8 bit shift registers. ..

RS-232 Protocol Analyser Y Cable

RS-232 Protocol Analyser Y Cable

In need for a cheap but effective RS-232 Protocol Analyser? Just make your own Y adaptor to enable the logging or display of data transmitted and/or received in ASCII, Hex, Decimal or Hex-Dump formats. A configuration file is included to allow quick setup and analysis. You can make your own "Y" cable by following the diagram below. It consists of a pass-through cable which is connected in-line with the link under test...

Variable Fan Controller

Variable Fan Controller

When the fan seized up in my source and I changed it to a type with much less noise, turned on my computer, the largest source of noise CPU cooler fan. The computer I have a boxed Pentium III processor in slot 1, which is practically dismountable and fan replacement would be difficult. "Boxing" is a type of fan with ball bearings and replacement of the type of plain bearing to reduce noise, while cooling, but not reliability. Another option was to reduce the fan speed. I tried the program Speedfan. This enabled to set the fan speed, but I was unable to convince him to regulate the speed according to CPU temperature. ..

PIC Programmer schematic RS232

PIC Programmer schematic RS232

In the article you will find a description of the universal PIC programmer, which suggested the involvement of Jens Madsen Dyekjar [ http://www.jdm.homepage.dk/newpic.htm ]. Program allows districts PIC12C5XX, 12C67X, 16C55X, 16C61, 16C62X, 16C71, 16C71X, 16C8X, 16F8X, serial EEPROM 24Cxx. It allows to program the microcontroller directly involved (ICSP) and other adapter series programmable components, such as ISO cards. When I needed some time to program the PIC microcontroller, I decided to build a programmer. This solution seemed more operative than I repeatedly asked someone on the programming of their friends...

LED output from SB Live! Value

LED output from SB Live! Value

Many modern audio recorders is now compatible with digital input S / PDIF (Sony / Philips Digital Interface). Devices like CD Changers, MiniDisc recorders, computer sound cards and the like. working with digital signal just with protocol S / PDIF. Digital connection of two devices, for example. sound card with MiniDisc avoiding D / A converter cards and A / D converter minidisc they bring to the useful signal to noise ratio and cause a linear, harmonic and nonharmonic distortion. Sound Card SB Live! Value is equipped with a digital output in a yellow 3.5 mm connector labeled DIGITAL OUT...

SmartCard adapter / interface for PC

SmartCard adapter / interface for PC

This smartcard adapter follow exactly the specification ISO 7816. Also, the protocol is the "asynchronous half duplex T=0 protocol" with "active low reset" and "inverse convention" as defined in this standard. The following description may be used in order to connect computers to ISO 7816 compatible chip card systems (e.g. GSM mobile phones or other pay-TV decoding systems) if they also use asynchronous transmission. For smart card systems which use synchronous transmission (e.g. most phone cards) the interface described here will need some modifications. ..

PC RS232 Frequency Counter

PC RS232 Frequency Counter

This circuit is a stable frequency counter accurate to 5 significant digits. The range is 0 - 30MHz with an input sensitivity of greater then 100mV. The probe connects to the PC serial port. So by using the crystal oscillator already present on your PC serial card and software calibration, the Probes' external circuitry is kept to a minimum. Probe 9 can also be used as a logic probe/analyzer using included software (LPROBE92.EXE)...

PC terminal using a TV

PC terminal using a TV

When you use microcontrollers in your designs, sometime you face a problem how to show user required data. Several LEDs, 7 segment display or LCD module can be solution. But if you must show a lot of information simultaneously, it can be difficulty. Large LCD modules are expensive and graphic modules require complicated control. You can solve it with a help of PC. Just send data via serial line to the computer and display everything on computer's display. I have had to solve the same problem some time ago. I have chosen normal small TV set for that. A lot of families change TV in this time because of digital broadcasting or modern flat and slim LCD and plasma displays. So they put older TV set away and it is dormant somewhere. Or you can buy older TV very cheap...

PC mains switch

PC mains switch

This project couldn't be any simpler if it tried. Using the PC's internal 12V supply to operate a relay, it is 100% reliable. If the PC is on, the peripherals are on and vice versa - it can't be otherwise (unless the relay fails). Other solutions have been suggested in magazines and the like, often using a USB port. The problem is that some PCs don't switch off the 5V supply to USB devices even when the PC is off. The auxiliary supply within the ATX power supply unit maintains a low power 5V supply all the time, and this is sometimes used for the USB ports to charge cordless mouses (meece?) or other devices...

4x15Watt 12volt power audio amplifier

4x15Watt 12volt power audio amplifier

While I would have liked a 4 channel chip with about 20 Watt per channel, the local parts store didn't have any yet, so I opted for two TA8215AH stereo chips, selected by their low price in this particular store. The design? Oh well, there isn't much to it. The circuit I used is almost an exact copy of the circuit suggested in the Toshiba data sheet. I only made a very few changes, but including an important one - the one that makes it possible to use this circuit in a computer, without getting power supply and hard disk noise! ..

Overvoltage protection for RS232

Overvoltage protection for RS232

RS-232C serial port lines are quite prone to be damaged by overvoltages. The damaged to computer serial ports have become more and more expensive to replace because of higher intergaration: usually you have to buy new motherboard if one serial port in it gets broken. So it is wise to use some extra protection in situations where overvoltages surges are quite propabe and repairing gets expensive. For examples of this type of situations are long serial port lines side the building and situation where the computer is connected to ungrounded outlet or the electricity distribution wiring is is not well organized...

RS-232 data buffer

RS-232 data buffer

This is a simple serial port buffer circuit I designed for a friend to speed up his SLIP connection in campus computer network "TRINET" of Helsinki University of Technology. The problem in the network was that the RS232 commections from rooms to terminal server were long and made of bad quality wiring. The circuit is a simple buffer which adds more driving capacity to PC serial port for the signal to go succesfully from PC computer to terminal server (other direction had no problems). The computer is connected to connector CON1 and the buffered output is available ar CON2. With this circuit the speed of RS232 connection to termial server could be succesfully raised for 9600 bps to 38400 bps...

Power from PC's RS-232 circuit

Power from PC's RS-232 circuit

The following circuit is an example how to get power from RS-232 serial port. It gives regulated +5V power for logic circuits and also unregulated positive and negative power supplies for RS-232 transmitting circuit. The circuit gives only few milliampres power output because the power available from serial port is limited (and resistors R1, R2 and R3 limit current more). ..

PC Microphone Preamplifier

PC Microphone Preamplifier

Soundblaster soundcard series (SB16, SB32, AWE32 and AWE64) have all a microphone input designed to be used with the electret microphones which come with the soundcard package (some packages) or with separate microphone designed to be used with SoundBlaster soundcards (there are separate microphones and some monitors have built-in microphones like this). Because the microphone input needs very high input levels it is not suitable to be used with any other micophone type than elecret capsule microphones. If you connect a dynamic microphone (which gives typically few mV voltage) and try to record it you will get very low signal level with lots of noise...

Sort List by: Alphabetic Date Clicks Rank ascending | descending

Neighbour Categories