Reading EM theremin schematics

Posted: 7/27/2017 12:28:23 PM
rob reido

Joined: 6/22/2017

I am looking to build a theremin based off the instructions in the February 1996 issue of computer music magazine. I have purchased a basic prototyping board from Maplin's, but, as I am completely new to electronics, I am unable to apply the information in the 2 schematic diagrams to a real-world application. Is there anyone who could possibly provide me with advice as to how to use and read the schematics provided in the instructions? Thanks in advance.

Posted: 7/27/2017 2:44:29 PM
oldtemecula

From: 60 Miles North of San Diego, CA

Joined: 10/1/2014

 

Rob said: "Is there anyone who could possibly provide me with advice"

Your first electronic project and of this magnitude should be done with a kit that has instructions and uses a PCB, anything else is pure silliness. 

Christopher

Posted: 8/2/2017 9:09:35 AM
donaldreid

Joined: 8/2/2017

rob reido is an bright, enthusiastic, teenage music tech student who decided to have a go at building a theremin using the article from emusician. The article pitches it as a relatively easy home build and I think it's reasonable, having read that, to think that it's worth giving it a go. With some help from his Grandfather who's a skilled fabricator he has built the antennae, casing, front panel and milled a mounting bracket from a piece of solid stainless steel. He's sourced all the electronic components and built the two antennae boards. The current work in progress build is already a thing of beauty.

He now needs to do the main circuit board. It would be great if we could get some advice on this, the article suggests using a plug in board and refers to one that's available from Radio Shack - but it seems to be an old item - so any advice on current similar boards would be great - I got the impression that the plug in boards don't need the components to be soldered so it sounds like a good way to allow him to figure it out.

We are also struggling to understand the schematic and layout for the main board, any advice as to how we could progress this would also be good - are there any resources on the net or books we could pick up to get some basic knowledge of how to translate the diagram into a physical build would be great.

It's really disappointing to see his efforts and request for help dismissed as "silliness" hopefully someone can come up with some more constructive advice.

Posted: 8/2/2017 11:03:05 AM
rupertchappelle

Joined: 5/8/2017

Theremineers can be rather crusty and rude at times. What you are trying to do is not silliness, but you will need to find someone who is into electronics and building things.

Without a printed circuit board you have to figure out how to use wires to accomplish the same result - connecting the components carefully and you will have lots of wires making it rather confusing.

If you have a picture of the circuit board there are places that could etch one for you or if you are bold and with your grandfather's help, there also are DIY instructions.

https://www.google.com/search?q=pcb+etching&oq=pcb+etching&aqs=chrome..69i57j0l5.4470j0j4&sourceid=chrome&ie=UTF-8

I wouldn't, but I am not a builder, just a player.

Rather than starting out with a full run, perhaps a short walk beforehand may be more encouraging. Art Harrison has a pitch only kit with the pcb and parts which will be an easier build:

http://harrisoninstruments.com/index.html#Products

Most DIY people are now doing Aruino UNO kits, but is that real or not, the one I made didn't sound too good, 

https://www.google.com/search?q=arduino+theremin+kit&oq=audrino+thermin&gs_l=psy-ab.1.1.0i13k1l4.5283.9415.0.18579.15.15.0.0.0.0.110.992.14j1.15.0....0...1.1.64.psy-ab..0.15.990...0j0i131k1j0i67k1j0i10k1.BHB_YWmwatY

Good luck and illegitimi non carborundum as they probably got ground down themselves a long time ago.

If you are going to play the theremin, ignore the flack and stay the course, which is about as easy as playing the theremin.

Hopefully a builder will chime in with some better advice . . .

Posted: 8/2/2017 11:11:31 AM
rupertchappelle

Joined: 5/8/2017

https://www.jaycar.us/

Posted: 8/2/2017 1:36:36 PM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

I agree with Christopher, a Theremin as a first electronics project is kind of asking for it, particularly if it doesn't have a printed wiring/circuit board (PWB or PCB).  You're having to learning how to solder, how to read resistor and capacitor markings, how to read schematics, etc. on top of building a fairly touchy circuit.  

For Theremin work you must have an OK digital multi-meter (DMM) and a decent oscilloscope.  Otherwise you're flying blind.  It really helps to have some sense of what's going on in an inductor / capacitor (LC) resonance circuit too.  Troubleshooting skills for transistor-based circuits will be necessary at some point.

Read some electronics magazine or web articles where they walk you through the circuit in the article (that's how I learned to read schematics - though I never really "got" how transistors worked until I studied them college).  Start with a simpler circuit or two on a plastic breadboard, then try transferring one to a PWB.  Baby steps.  You don't wake up one morning and decide to run the Boston Marathon that day.

If you look at the way the old Heathkit company handled this, holding noob hands and walking them through the building a color TV with no past electronics experience, there is always a PWB, the components are in labeled bags, and the instructions are extremely explicit with pictures / diagrams, broken down into very clear, brain dead steps that a monkey could follow.  Even then, they had extensive phone tech help, and a service where you send them the board and they fix whatever you did wrong.  Working there must have been a nightmare, every day must have been like talking a stewardess through the landing of a 747.

For a first Theremin without PWB, I'd recommend you get your feet wet with the pitch-only Thierrymin.  That will give you some general experience with everything you're currently up against.

Posted: 8/2/2017 3:33:54 PM
rupertchappelle

Joined: 5/8/2017

Thierry is an excellent source.

 

Posted: 8/2/2017 6:25:02 PM
donaldreid

Joined: 8/2/2017

Thanks for your help with this. 

We have now realised what the diagram that was baffling us is actually saying. In the article Fig 4 shows a layout for the main circuit board, there are lots of things that don't appear to connect to anything else - this was what we couldn't understand. We have now realised that the method proposed relies on a prototyping board called an Archer experimenter - which is basically a breadboard with 6 rows of connector strips. Once we'd grasped this and had superimposed the diagram onto a representation of the board it all makes sense. The diagram is in fact a complete and precise layout for the circuit board - it just doesn't have the underlying board structure on it. 

So - theoretically if you were to follow that diagram and not make any mistakes - you'd be good to go! I realise that's easier said than done - especially as it looks like the board isn't available any more so we'd have to figure out a way of reproducing it from what we can get now.

So we'll give some thought to your suggestions - can see how it would be good to start on a simpler design. But at least now we understand what we have to do to move forward on the project we've started and can make a more informed decision :)

Posted: 8/2/2017 8:26:52 PM
oldtemecula

From: 60 Miles North of San Diego, CA

Joined: 10/1/2014

Ok ok maybe my use of the word silliness is too harsh for children; I should have said foolishness.

Anyway you may already have this, but here is the authentic info the magazine builder was using.

The EM Theremin Authentic Info

The great musician Coalport always said something like - most people that want advice usually just want you to agree with them. -

No matter what theremin you build you will learn a lot and that is what's most important. In all my years of original theremin design I gave everything away at no cost because I know how challenging theremins can be and most youth do not have a lot of money.

If someone does not hear a sound byte of a particular theremin design before they set out to build it, they will most likely be disappointed, now that is foolishness. 

Christopher

Posted: 8/3/2017 1:04:48 AM
xtheremin8

From: züriCH

Joined: 3/15/2014

maybe not of much help, but some diy smartass thoughts crossed my mind:

fig.4 shows the layout for all the parts. the schematic shows how it's all connected. print the layout and draw the connections first with a pencil. it's much easier to avoid mistakes than to fix them later on. if you "mirror" your sketch, by scanner/computer/photoshop or whatever,you have a nice view for the backside, where the soldering is done. 

if you cant't find that archer experimenter board(judging by the foto, looks like a breadless breadboard to me), you could go with normal epoxy perfboard, the one with the copper-eyes. and run the connections with thin *wire. (or bend the legs over from the resistors for short connections for expl.)

*whats best for that job? stranded? as thin as possible? 

btw. LM 13600 can be swapped with a 13700. just in case.

seconds on dewster's post: go for the thierrymin, too. but you will anyway, sooner or later! it's an addictive thing, theremins.

sometimes overseen:"search" is your friend here. theres a lot of mindpower stored and you aren't the first ones building that model. thereminworld is full of awesome.

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