8 Channel D/I Card for RS232 Schematic Circuit Diagram

The author is a student at the Electronics Department, Technological Educational Institute of Piraeus, Greece. This project is a card with eight optically isolated TTL-compatible inputs for external connection to the serial port, which communicates through the RS-232 protocol. On this card, you will look in vain for a UART or microcontroller chip because the[…]

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±5-V Voltage Converter Schematic Circuit Diagram

Asymmetrical ±5 V power supply is often needed for small, battery-operated operational amplifier projects and analog circuits. An IC that can easily be used for this purpose is the National Semiconductor LM 2685. It contains a switched capacitor voltage doubler followed by a 5-V regulator. A voltage inverter integrated into the same IC, which also[…]

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Power-On Sequencer Schematic Circuit Diagram

This circuit was developed to turn on power supplies in sequence, and then turn them off again in the reverse sequence. This can be helpful for experimenting with equipment and circuits whose power has to be applied and removed in a particular order (like the PC/EPROM-Programmer combination used by Elektor’s Software Service Department; Ed.) The[…]

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