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Here is a circuit to generate sequentially running light effects using a simple program written in C. The output of the program is taken from the LPT port of a PC and then fed to the interfacing circuit for the LED display. The outputs of the interfacing circuit are decoded, inverted, and then connected to LED s through optocouplers.   Fig. 1: Interfacing circuit for PC-driven LED display The interfacing circuit along with the 25-pin parallel port is shown in Fig. 1. IC1 (74LS138) is a high-speed 1-of-8 decoder/demultiplexer. In the circuit, only five outputs (pins 10 through 14) of IC1 are used. These outputs are inverted using  NOT gate IC2 (7404). Optocouplers IC3 through IC7 (MCT2E) are used to prevent the circuit from damage in the event of short circuit in the load.  Thus the loads comprising LED blocks LB1 through LB5 are isolated from the interfacing circuit including the PC. Each LED block contains a number of LED s connected in series. The LED s can be arrang...

This is the Simple Cathode led Display Circuit Diagram. Teledyne TSC7135 DVM chip is used to drive a multiplexed 5-digit display. A CD4513BE CMOS IC, for common cathode drive, is used as a segment driver selected by pins 17-20 of the DVM chip. The transistors can be any suitable npn type such as 2N3904, etc.  Simple Cathode led Display Circuit Diagram

Infrared light has a difference with ordinary light in general. We can see clearly when a light or light on an object. As with the infrared light we can not see the manifestation of these rays. Frankly I can not answer when asked why the infrared rays are not visible in the eyes of us. So at night do not hope you can make light by using infrared light. One thing that is often heard from many people that infrared light can utilized for the functions of a camera that can see in dark conditions is often called an infrared camera. Actually I have explained the working principles of electronic circuit section in this blog is about the basic working principle of a series of infrared sensors are simple. To design this sensor circuit you should not find trouble if you ever make another series of sensors. It's just that the sensor circuit consists of the transmitter and receiver, to learn the basic principles of this series of infrared you can see in the Basic Principles Series Infrared Tra...

This charming little circuit is a genuine four-digit running-text display, complete with a Christmas / New Year’s greeting. Naturally, any competent programmer can easily arrange to have a different text scroll across the display. The associated soft-ware, including the source code, can be downloaded from the Free Downloads section of our website or obtained from Readers Services on diskette (order number 020365-11). Circuit Image : As can be seen from the schematic, the hardware consists of little more than an AT90S1200 microcontroller, a 4-digit LED display and a 5-V voltage regulator. The only external circuitry needed by the microcontroller consists of a reset circuit and a 4-MHz crystal, and the remainder of the components are limited to a few decoupling capacitors. Mini Running Text Display Circuit diagram :  In the prototype model, an Osram SLO2016 display module was used. Although this four-digit module measures only 10×20 mm, it provides an especially clear and bright disp...