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Universal S/PDIF Converter

So far: Only the prototype

This is a simple circuit using a RS-422/485 receiver/transmitter to receive a signal from the coax S/PDIF-input and to drive the coax S/PDIF-output.

Both the optical (TOSLINK) and the coaxial output can be switched individually either to the optical or the coaxial inputs.

S/PDIF Converter, click to enlarge

Relatively cheap components can be used for up to 48 kHz sample rate. For up to 96 kHz things become more expensive.

S/PDIF converter circuit diagram

Up to 48 kHz:

Up to 96 kHz:

All components are pin compatible and may alternatively used.

The 96 KHz version does not work properly as the MAX3462 does not work properly! Obviously there is a design error in the MAX3462: When the device is wired as a simple RS-422 repeater (pins 2 and 3 connected, source impedance 75 Ohm, no load) a strong spike after each falling edge can be observed. This might be due to an internal feedback from the RS-422 output to the RS-422 input. I do not have a remedy yet. Currently the full duplex operation with both directions carrying data and the S/PDIF repeater modes are not applicable. (A S/PDIF repeater mode with a detour via TOSLINK works!)

Maxim RS-244/485 Receiver/Transmitter MAX3462

The board is designed to fit in a cheap Teko Al Box 2/A.1 which is shown without a cover here.

S/PDIF Converter in Teko Al Box 2/A.1

Last update: April, 22nd, 2005 Questions? Suggestions? Email Me! Uwe Beis