[sdiy] MIDI specifications

[Ingo Debus]

Magnus Danielson wrote:
>>what would this do or prevent? it seems to work as it is.. a small wooden
>>teabox with some holes for the midi ports i've just soldered wires from the
>>input-pins to each output pin.
> 
> 
>>From the output you have a current, it's going to drive 5 inputs now, which
> means that the opto-coupler runs at the fifth of the current it is supposed to
> run at, meaning less emitted signal and all that. If it works it works, but you
> have just moved from one case of a limit into another. Also, all of a sudden you
> want to run another pair of boxes in the same time, so you hang them in too...

The biggest problem here seems to me is that there are now several 
LEDs in parallel with a common current limiting resistor. Those with 
just a slightly higher voltage drop won't light up well.


> By using a single chip and a small handfull resistors and a opto-coupler, you
> have built yourself a propper MIDI-splitter. My point is that it isn't as far
> away, so why not do it properly? As it is now you survive over the weekend, but
> is it the long-time solution?

Well, it would need a power supply...

Ingo