So, I’m trying to figure out how to convert midi signal to contact meaning, I got this amp head and the channel switching is done by a contact (TS in the back, open / close) and I would like to control it via my FX processor which has midi out.
At the beginning I thought to do it with an Arduino chip but than a friend recommended I can get along with optocoupler also.
To be honest both are new for me, I know these exist but have zero experience / understanding how it works.
Ideas? Schematics? What is better (in terms of ease of building it and complexity) for me, Arduino or this optocoupler?
I had the impression I will need either:
Arduino (midi signal receive and process) + relay pack (final contact, what will be connected to the amp channel switch input).
Arduino (midi signal receive and process) + This optocoupler (instead of the relay pack).
Your MIDI OUT device is designed to send a 5v switching signal out to another MIDI device with a optoisolator.
The optoisolator has a tiny LED inside of it. That is the MAX LOAD you want your MIDI OUT device to drive. Try to source too much current for anything else and you could damage your MIDI OUT port.
The main reason for the optoisolator was to eliminate switching noise… you don’t spend $5k on a keyboard in 1980 for a SC Prophet V and get to listen to a buzzing sound.
Granted your arduino isnt a source of sound output… and you could possibly try something different to get the MIDI signal to the arduino w/out a optoisolator…, but why risk sourcing too much current out of your MIDI OUT device, thus possibly frying it?
So what you want is:
your MIDI OUT device–> optoisolator --> arduino --> relay
is the chain you are seeking.
The relay could possibly be a transistor or mosfet or 4066 bilat IC… hard telling w/out seeing how the amp TS is wired up.
Relay is the most direct method.
But the hardest part for beginners is coming up with code to write to the arduino so it will listen to the MIDI commands, filter out what it doesnt want, recognize what it does and activate the switching device.
I’m starting to have a clearer picture in my head about what I need.
Actually, I’m less concerned about the code as there are many examples like this over the web, I guess I will start with something and continue from there trial and error….
Any suggestions for part numbers and type, where to buy and the most important, circuit, how do I connect the parts?
I’m a practical electricity engineer so I can read circuits and understand them more or less.
Thanks again, very nice of you all to help and answer so fast.
I use a 6N137 optoisolator. TONS of examples used with Arduino can be found in a search.
Can be bought all over the net… I bought several from DigiKey since the Co. I work for buys parts all the time (I piggyback on their shipping…)
Arduino in it’s many forms… I’d probably check into a Nano since they are cheap.
Relays… There are many “module” boards on ebay that are ready to be used with arduino for cheap from China or pay extra from USA or your local country.
Schematic is usually simple… the 6N137 only needs two resistors and a diode (see examples)
Connect the 6N137 to the arduino and have a 5v Pin OUT from arduino to your 5v input of your relay…
Hook your amp’s TS to the relay.
What is the limitation for relays? I thought of heaving 3 or 4 but if it’s only a matter of the relay board itself, I might go with 8 as if I’m already doing this, I will build something that can switch many devices like the tuner “Mute” on the pedal board for example (it has also a TS input) and others.
No. this is my first ever with Arduino, never tried / touched it.
I have a very good tech approach and I can read and understand schemes so…how hard can that be…… right?
I will order the 3 parts and return with questions once I receive everything and try something with it.
Thanks for now.