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Saturday, November 2, 2019

Making a Theremin

The theremin has fascinated me for many years. Recently I watched some YouTube videos on how to play it, and got the urge to give it a try. Apparently, it's easier to play if you have experience with the violin -- an instrument I played, and hated, for 7 long years. So I figured I could give it a go. The instrument itself costs at least $450, but I found a $100 kit on eBay and purchased it...

... Not realizing you need an electrical engineering degree to assemble it! Where's Jesse when I need him?

In Natural Harmonics (Wynter Wild #6) Jesse is anticipating (without much joy) going to see an ambient band with his girlfriend Dusk, and there's mention of a theremin:

Unlike Jesse, I find the eerie theremin fascinating because it is (from Wikipedia): "controlled without physical contact" from the performer. This electronic musical instrument varies the pitch and volume of the "music" when the performer moves their hand closer to or further from two antennas (something to do with oscillators and capacitors, don't ask).

Fortunately, about a month after I bought it, my electronics-minded brother-in-law visited for a week and helped me out. Here are the pieces included in the kit -- the fiberglass circuit board, the black box casing, the speaker, the antenna, and all the components.


And here are all the extra things I had to buy (another $100, although most of it is reusable of course) -- a multimeter, soldering iron and accessories, and plug kit:

Here's my husband and his brother struggling over the instructions. I will say that my husband was convinced it would take weeks to put together, and that one wrong solder would render the thing useless. Of course I took this as a challenge! Let's see if his lack of faith was justified...

After identifying all the pieces and getting a quick tutorial on the soldering iron, I started attaching the bits to the circuit board. First, I bent each resistor using the gauge and poked it through the correct holes on the circuit board.


I trimmed the ends on the back and applied some flux pen, a liquid that helps the hot solder flow.


Then I soldered the transistor, making sure it ran through slightly to the other side to make a good connection.


There were about a hundred of these things to put into the correct slots. The company that puts together the kit (Jaycar), based on instructions in an electronics magazine, doesn't always use the same name for each part as the magazine article, so you have to match everything up. They need an editor to get themselves in order!

Here's the reverse showing all the neat little joints:

 A few more components added. Every single one has to be a perfect solder in the right place!

I like this shot because it looks like a city of high rises:

The final board with the switches and LED light soldered in place. The half-oval on the left is the volume control panel.

The board is put into the box with the speaker and antenna, and voila!

The main lesson to be learned here is that my husband was WRONG. My theremin worked right first time -- here's my daughter testing out the pitch control:

This thing is not easily controled. My volume control doesn't really work at all, so I've given up on that. The pitch control needs very subtle finger movements to play a tune and I'm still learning. Hopefully I'll have a tune to show off soon.

Here's the link to purchase the kit on ebay: Theremin

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