A quick update tonight.
All the things I need to build the boxes for the next run of Magnetic Cellos have come in. Switches, power switches, battery drawer, tuners are now pressed, screwed, or otherwise mounted into their respective cutouts in the metal boxes.
5 box tops and bottoms, with hardware
Installing these parts was the easy part, though. Actually building a working instrument means wiring this parts together, and that means another large bowl of Rainbow Spaghetti:
Rainbow Spaghetti, aka color coded wires
So far, I have mostly finished wiring together only one box. But, after testing out the complete electrical package, I’m very happy with the results. The coil responds how I hoped it would, and the variety of tones give the instrument a lot of versatility. The original square, reedy tone is still there, but now there are two smoother, flutter tones, and… a mode that can only be called “Dubstep”. Think “Wub Wub”. This last tone is actually a happy accident; I was expecting a sine output when I stuck the BJT in the circuit like that. But I like the tone, and think it deserves a place on the instrument… on the far end of the tone knob.
That’s all I have for now. I’ll be testing the last few functions on the first box, and then wiring together the rest of the boxes over the next few weeks. More Rainbow Spaghetti headed your way.
Looks like all those hours triple checking my drawing have paid off. The wooden bodies have come in, and everything is to spec. The box, coil, and wooden body fit snugly, and the holes in the box line up with the screws in the coil housing:
Custom box and body, fitting together with the coil.
These holes are used to hide the screw heads from the coil housing
Also, all of the little bits of hardware that go on the box-the power switch, tuners, tone and volume knobs, fit right into their intended locations:
Audio out, end pin connector, tuners, and power switch, with the coil on top.
Tone and volume knobs, bow cable connector, with the circuit and battery holder above.
So now I have all the custom parts I need to make the next batch of instruments! While it took a half year to figure out the logistics of specifying and then ordering special parts, bringing in professionals has really boosted the polish of the final instrument. It looks like the 8 days I spent cutting up wood, and the 2 days right after that I spent drilling holes in boxes, was a one time thing. Now I have the help of a metalworking shop and an old school woodworker.
The plan is to solder together as many boxes together as I can in my free time, and to assemble entire instruments during winter break. In the meantime, these guys will be chilling on the couch:
I visited the woodworker a few days ago to check up on his progress on the instrument, and saw something amazing:
The woodworker had five maple necks and bodies built for the next magnetic cellos. I checked up on the quality of the work, and while I was there, we discovered a clever use of a dowel to keep the joint between the neck and body from wiggling. We also did a drop test to test the strength of the wooden body…
… and I chose a stain color that would bring out the orange from the copper coil. My woodworker will be sanding, staining, and finishing these instruments over the next few weeks.
Oh, and earlier today, I had a chance to solder together one of the new circuit boards. The new board works as expected. With better components, reworked tone filter, and more sensitive coil amplifier, this circuit is a small but noticeable improvement.
Unfortunately, it looks like it is still going to be a few more weeks until the custom metal boxes come in the mail, which sinks my plans of building the next round of instruments before fall classes start again.
Don’t worry, though. If I run out of magnetic cello things to work on for a while… there’s always the Guitar Chord Card. The new cards and stickers came in, and all I have to do now is actually figure out how to sell it.
A few days ago, I finished laying out the PCB for the next batch of magnetic cellos, and with that, this round of design is done. Since April, I’ve been working to make the instrument a little bit better and alot easier to build. Now it’s time to build those next instruments.
Instead of doing everything myself in my parent’s garage, I’m getting help. The wood is being done in Morro Bay, magnetic bows and coil housings will be laser cut in Oakland, the PCB’s are being printed in Malaysia, and the metal boxes are being machined somewhere in New York state (I think, or possibly Canada). The other electrical bits and pieces are coming in the mail from Digikey and Mouser.
There’s not much more to do now, but to wait for parts to come in. I’ll let you all know how the timing works out, some of these custom parts have a lead time of more than a month. In the meantime, here’s the PCB I designed:
PCB of 7.2 magnetic cello.
I suppose I can relax and do non-cello things for a while, it being summer and all.