S/PDIF input

From HwB

S/PDIF input circuits

The following circuits can be used to convert S/PDIF signals to TTL level signals which can be connected to any suitable output circuit or directly to digital electronics.

1 Circuits
- 1.1 S/PDIF coax input circuit 1
- 1.2 S/PDIF coax input circuit 2
2 See also
3 Contributors
4 Sources

[edit] Circuits

[edit] S/PDIF coax input circuit 1

                                    ----10K--
                      10 nF        |         |
                       ||          |    |\   |        |\
S/PDIF input ------ ---||----100R-- ----| O-- --- ----| O----- TTL out
                   |   ||               |/       |    |/
                  75R                           10K
                   |                 74HCU04     |
                  ---                           ---

This circuit is part of circuit "Splitter for S/PDIF coax/optical output" by T. Giesberts from Elektor Electronics magazine July/August 1995 pages 78-79.

[edit] S/PDIF coax input circuit 2

                             ----10K-----  5V
                            |     /\
                           ---     |
                     4700 pF       |
                       ||          |    |\            |\
S/PDIF input ----------||---------- ----| O-----------| O----- TTL out
( /-500mV)             ||               |/            |/

                                         7404

The capacitor works as DC blocking capacitor. 10 kΩ trimpot signal raises its ground potential to the point that Hex Inverter IC1 recognizes the difference between a digital 1 and 0 input. When you firt test the circuit then first addjust 10 kΩ trimmer to the center and then adjust it so that the circuit receivers the S/PDIF signal well. If you have a voltmeter, you can adjust the trimpot to show around 2.6V at pin 1 of the IC. The inverter buffers the input and produces TTL 0-5V output signal. This circuit does not provide the 75 Ω termination resistor, so you need to add it if you have problems because of cable signal reflections. This circuit is part of Coax Digital Out to MD circuit design.