Earlier testing and use had proven that the midi out signal from my little Arduino Uno based projects was far too weak to drive the signal over a long MIDI line so I’ve been researching how to boost the signal. I found a circuit on the internet that uses a BC212 PNP transistor as a driver however it seems the BC212 is now obsolete but can be replaced by a 2N3906.
This is the circuit I found:
I’m not using the input side although I am now starting to add something similar to my MIDI hardware circuits just to protect the Arduino and to make them conform to the spec although I an using 6N138 isolators.
Anyway, back the output side of things. I knocked up the output circuit on a breadboard although I omitted the 220 ohm resistor from pin 5 to ground and used a different pin on my Arduino for the output so that I did not need the ‘programming switch’ in there for my little test.
Threw together a little test program to continuously send out a MIDI CC command with changing data so I know it’s working because I can see the differing data. The command was actually a BeatBuddy MIDI volume command. Hooked it up to my iPad via the iRig and gave it a try. Once I knew it worked with a short MIDI cable I tried it with a long cable, around 20 feet long. Success:
With it all working a connected it up with the long cable to the BeatBuddy and was able to see the volume setting change on the BeatBuddy.
With all this working, the next step is to integrate these changes, plus the functionality of the BeatBuddy MIDI Volume Control (BBMVC) into the Hackman, my magic box that makes the Jamman Solo XT and the BeatBuddy work together. For that though I am going to try to design a ‘real’ circuit board in Eagle and then have the board made up as by that time,it’s going to be getting far too hard to squeeze everything onto a small prototyping board and solder all the connections by hand. Plus it just takes far too long!