More coils

Here I have started to wind the solenoid coils using 0.25mm diameter magnet wire. A 25g spool filled up 4 solenoids nicely, I didn't worry about counting the number of turns.

The winding jig was very simple. Just a crank handle made from a couple of 3mm screws and a scrap of 2mm aluminium. The bolt in the vice is being used as a pin, the thread isn't being used. The spool of wire is being held behind a couple of bits of steel, ground parallels in the case, this keeps a bit of tension on the wire. I just used my finger to guide the wire to get an even distribution. The winding took about 2 mins per coil.

After winding I soldered longer wire leads to each of the enamel wire endings. The soldering process removes the enamel, so you don't need to worry about scraping it off. I used some shrink tube to protect the join.

After successfully winding 6 coils, that brought the total to 8 including the prototypes. Enough coils for a single octave and a good chance to test out playing some songs.

Here is a fast version of the "doe a deer" song from The Sound of Music. This was about as fast as I could play with the first prototype coil. It required a 100ms pulse while the later design with more windings only needed a 7ms pulse to get a note to ring. So when all the coils are wound it will play about 14 times faster than this, which, after a little test, is ridiculously fast.

Solenoid spools.

Now that the test solenoids worked well it is time to get stuck in making the rest. Starting off with the spools.

Here is the design.

Turning on the lathe. I had to use a the tail stock and turn between centres as the nylon was deflecting. I think a more machining friendly plastic could have helped. I had more deflection problems with the drill producing a well undersized hole and ended up using a 6.5mm drill.

All finished.

Circuit Progress

So I spent a little time getting the chain of 4 shift registers to behave and now have 32 output pins to play with. The glockenspiel I made has 25 keys so things should work out well.

I also wound a second solenoid coil of a slightly different design to the first. I used 12mm nylon for the spool which allowed for some more windings than the first.

The circuit to actuate the solenoids is similar to one shown on the arduino forum.

I am now using a new Arduino Uno purchased from ebay au store microcontrollers and more.

Here is the result with both solenoids connected.