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 interface described in this article is based on a Microchip PIC16c84 microcontroller.
12C508 controller provides both bit-rate detection and a synchronous, appended-clock output from an asynchronous input-data stream
This converts the midi signals to visible light pulses. Just the circuit and plug it to the MIDI output of your computer. When computer sends any midi data out, you see the LED flashing.
This shows how to get sound from computer to telephone line. A circuit that would let you connect any Mac to almost any phone circuit.
This circuit is a simple adapter for PC parallel port to think that there is a printer connected to computer. This adapter is useful for testing printing speed with different software and as a part of your own designs.