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Serial and parallel port circuit diagrams

April 28, 2010

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... [more]

Parallel Port Relay Interface

April 28, 2010

Parallel Port Relay Interface [more]

PC Serial Receiver

April 28, 2010

PC Serial Receiver (57.6K Baud / TTL & CMOS) [more]

PC Serial Port Receiver

April 28, 2010

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. [more]