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SPDIF Selector

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We had a brief discussion about coaxial SPDIF switches >> here <<.

My experimental board got finally put together, and I have been testing it since a few days, with my 930, 940 and JA20 hooked up.

I have attached the project files [projectfiles.zip] for those who want to build their own. The schematic is very simple, and can easily be developed further, like when someone needs more inputs, or wants to change channels with push buttons or IR remote instead, etc.  Components cost about 12 Euro, plus the "soapbox", that is just a cheap small project box, to protect the board. I did not feel making a fancy techno looking chassis, even the rotating knob is from a salvaged 510S.

The device has three SPDIF inputs and one SPDIF output (that is galvanically isolated, to avoid ground loops). It works from a 5...6V DC adapter. One LED is lit when the box is powered up, three others are lit respectively to the actually selected input channel, also matched by the position of the rotary switch (*). I chose a 4 throw switch, and used the leftmost position for muting the output (only the power on led is lit) - can be handy when swapping cables, for example.

(*) One comment on the board: depending on the actual rotary switch model, switching order can be different. I had to tinker the board after it turned out, that the switch I bought worked the opposite way. In practice it meant I had to swap the connections of LED1/LED3 to pin C2/C4, also, ground pin B4 instead of B2.




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  • 1 month later...

That looks great NGY - much better than the "cheap and cheerful" 2 way switch I bought.

If I decide to mess about with any further connections I might have a go at building one, although I suspect it might be a bit tricky for a total novice.

How easy would it be to modify the design to incorporate optical connections too?



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  • 2 weeks later...
On 2017. február 7. at 0:45 PM, BearBoy said:

How easy would it be to modify the design to incorporate optical connections too?

It depends on the final goal.

This multiplexer IC (and the encoder switch) can handle four channels. As one position is currently used for "mute", that can be converted to an optical input. One coaxial input can be replaced by an optical receiver quite easily, also, adding an extra optical output (or more) is not a big trouble. These would be relatively small additions/changes to the original circuit/board.

However, if two or more additional optical inputs are needed, besides the existing coaxial channels, that would be a different circuit. It is certainly doable with discrete logic ICs, but it would probably make better sense to build the new circuit around a microcontroller and a few push buttons instead. (And adding IR remote control is much easier, than to the current device.)

As for building one: there are PCB making services available, so no hassle eith etching, drilling, etc. at home. Some level of soldering skills is certainly necessary, but other than that it is a pretty easy assembling task. ICs are in sockets, and the passive components are not that destructable, even for a hand without practice.

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