Liz's VPO Project

 Here they are, my gently-used Stop Action Magnet units. They were removed from a project by the previous owner and stored likely in a garage, they needed a bit of cleaning.  Now they are all ready to prepare for installation in my organ console. These are for flip tab stops. A little plastic bit with the name of the stop engraved on it gets screwed onto the little metal tab.  Pushing the tab down activates the stop and flipping it back up closes it. There is a reed switch, visible on the front side, that lets the computer figure out the current position of the stop.  It can be polled like the keyboards to discover if the organist has flipped it.   The tab can also be flipped by the computer - by activating one of thise electromagnet coils. If you push a piston button, it activates a bunch of stops in Hauptwerk. Hauptwerk can then send MIDI commands out to the console to instruct it to flip the tabs to match the current state of the virtual organ...

Everything proceeded according to plan in the last week.  I built the second sensor array, incorporating everything I'd learned making the first one, and installed it into the Great manual. I took the first one out and corrected the misaligned sensors (I only had to remove and replace 4 total. I was able to scootch the boards of 8 sensors back and forth to get most of the others lined up correctly.  Then I installed that array into the Swell and plopped it into the organ for testing.  A couple of rounds of correcting wires and nudging magnets and it is good to play! You can on the right side of the left photo, the Mac Mini I acquired to dedicate to this project. It is a new model quad core i3 with 16GB memory and 128GB SSD.  I know I'm going to need a ton more disk space but I'm figuring on adding an external drive.  I borrowed a monitor I use for my work laptop to get going - I'm still pondering what I will want to do for screens on a permanent basis b...

I finished building the first Hall sensor array, and after not small amount of fiddling around, figured out how to install it into the manual.  It works! So, now to back up a bit and document what I did.  I build the sensors into strips of 8 for ease of handling (and one short one of 5 because 61 keys) I bought 160 Melexis  US5881LUA-AAA-000-BU sensors from Mouser. With the front (beveled) part facing me, the left pin is power, center is ground, and the right is signal. I happened to have a roll of 1/4" copper foil tape so I figured I'd experiment with using it as ground and power bus, it doesn't take much room and can be soldered to. I put a strip on the front and back of a piece of flexible proto-board.  The flexibility wasn't especially important here, but being able to cut it easily was . The legs are a bit fragile, but I didn't break more than one or two before I got the hang of handling them. Bending them with pliers works better than fingers. I pulled ...