I've been creating a MIDI Thru box project and was trying to avoid having so many resistors. Points A-G may (or may not) have a load connected to them. Are these equivalent, or do I really need to include a resistor on each branch?
Here's the circuit image
Is the current/resistance/voltage equivalent from the DC supply to each lettered branch in each circuit? More importantly, can anyone explain (or provide a link that explains) how you came to the conclusion? I'm a developer just starting to learn electronics.
I've gotten mixed responses on twitter, and someone mentioned asking here.
Best Answer
Pete, I don't know much about MIDI circuitry, but it appears that the outputs are simple open collector circuits with pull up resistors and inputs are opto-isolators. If that's not reasonably accurate, then somebody please correct me.
Given that understanding and assuming that the power supply you're using is adequately large so we can assume it'd capable of providing as much current as you want, then you could think of the two circuit options like this:
Circuit A is treating each of the inputs A-G independently and what's happening on input A isn't affecting what's happening on input B.
Circuit B is shorting all of the inputs A-G together and just happening to supply a bit of extra current to the mix. Anything happening on Input A is totally messing with what's happening on Input B. If Input A is trying to be +5 v and Input B is trying to be 0v, then you've got the outputs of two other boxes fighting each other and neither is working correctly any more.