Build a Pocket Theremin on the Cheap

CDs photocells, fir shame! Not very WEE/RoHs friendly are we?

Do you really understand what RoHS means?

It means you can now throw electronics in the trash instead of recycling them.

More important, it means that there is no more lead in the solder used to make electronic devices. Good, yes?

No. Very much no.

It means that a TV or any other device made from now on will last from 5 to 10 years, 10 years max, before it fails, and then it will be thrown away. It is a boondoggle for electronics manufacturers. And it's because solder without lead makes whiskers. This used to be a small problem when parts were large and well separated, but now parts are very small and close together. So when a tiny whisker grows from the tin, which it always does, it has a very good chance of touching another trace or part. And then, things stop working. Right now. No repair is possible.

RoHS is bad. Wasteful. And the manufacturers love it, because every TV, radio, cell phone, and even satellite, will have to be replaced in 5 to 10 years, instead 20 or 30.

Thank you European Union.

tom
K0TAR

Very cool but not my thing.Matthew T. Gossar

Hate spoil the fun, but RoHS compliancy doesn't mean you can throw your electronics to trash. It is just that this kind of improper discarding is not that harmful for the environment as would be if the solder material would contain lead.

Whiskers are not a problem with modern solders. After studying the reliabilities of lead free solders about six years, none of the studied materials presented whiskers. And this was done on flip chip connections, which are scale smaller than current smd so whiskers would've been more than noticable.

Main reason for current electronics not lasting longer than about 5..10years is the half ass job done in designing the products in first place. The curse of mass production; buying new one is cheaper than repairing. Mainly due to popular demand of cheaper products.

@Tarball:

It is funny to read what you think about RoHs, but your thoughts have no contact to reality. First, RohS didn't allow you to throw things in normal trash. Second: Electronic devices will only last 10 years in future? Wow, that means, the average lifetime will be doubled.

Please don't tell people they should not talk about a topic if the don't understand it if you do not understand it yourself. ;-)

Why is everyone such a nature-nut here? Your rhetoric borders on hysteria.
I highly doubt any of you have stopped driving your cars, stopped runing your computers, stopped playing your stereos, stopped heating your water, stopped turning on lights when its dark or made any other significant lifestyle change.

Lets talk about Pocket Theremins, not some tiny piece of electronic waste. How about you tell me how yours works?

This is a great article. I've always wanted to create my own electronic instrument and this is IT! THANK YOU and YOU ROCK!

HOWEVER, I have a few questions. On the bottom chip is a .01uh thingy and above it is a joint without(what my guess is) no solder/icon/bullet icon thing-a-ma-doowee. What gives?? Everywhere else I can see black-bally solder joints. HELP!

Also the 5k potentiometer... It has three parts I can solder wires too. How can I find out where I connect the wires?

PLEASE HELP! I failed this weekend due to a lame solderer and oh yeah, the schematic doesn't tell you which end is up on the chips soooo, yeeeah. My first attempt didn't make it past the leggs falling off of the chips, (careful, they are thin and break easy) but even if I did finish it and it followed the schematic exactly, I wouldn't have known that my chips were upside-down. Fortunately I found a site about the 555 chip and my second try will hopefully work... hopefully. :)

Oh, and by the way, the chip has a inset curve on one end... that's the top where the ground and power go. That's for any future DIY-fers needing to know.

1) The "bullet" is a junction point. That dot is telling you that you must make an electrical connection there (i.e. solder the wires together). If the wires cross and there is not a dot, then they should not be connected.

Be careful, though, some schematics are sloppy and don't always make things clear. Also, some schematics will have a little "hump" when two wires cross (but don't connect), to make it easier to determine if it's a junction or not.

2) For pots, you're always going to wiring the center pin, that's the wiper (the arrow in the above diagram). Your other wire will go to either the left or the right (viewing from front/shaft), depending on desired behavior.

If this is a volume control, I'd say put it on the right, that way your resistance goes down as you turn the pot clockwise (lower resistence, in this case, means greater power to speaker = louder). Worst case, you'll wire it backwards and the sound will go down when you turn clockwise. Just swap the sides. Pots are pretty hard to kill at these voltages.

3) I'd recommend picking up a little "breadboard" and using that to practice with, as you can focus on the circuit and not your soldering skills. Once you have it breadboarded up, and have it working, then you can solder it up.

Also, see if you can pick up some sockets for the chips. That way you can solder things together and not have to worry about overheating the chips in the process.

4) The 555 has been around since the early 70s, so there's a lot of documentation out there. Very widely used for blinky-stuff, etc. I've found this site to be very helpful: http://www.kpsec.freeuk.com/555timer.htm

We need to treat the earth better or we all die!!! Recycle ur stuff, don't trash it!

This is awesome. A simple Theremin operating on 2 timers. I love it. Having built some more advanced Theremins it's nice to see an easy, simple design like this.

Honestly people this is simple electronics and you can put it together in less than 30min. In fact with little effort you can just output the output of the Theremin to a stereo system line in and give the neighbors some interesting sounds.

Many thanks Dave.

I think what cybersamaurai is asking is whether pins 6 and 7 of the second 555 need to be tied together, and the answer appears to be "yes". The schematic shows a T-type junction with no black dot, and I originally put it together without the jumper between the two pins and got no sound.

I haven't built anything for years and was able to breadboard this up in less than an hour. Half that time was probably spent cleaning my workbench... My CDS photocells haven't arrived from Electronic Goldmine yet, so I used a couple of phototransistors I had lying around (NTE3035A) and got sound out of the circuit.

Thanks for a fun evening!

This signals the beginning of a beautiful hobby for me. I had never soldered anything before, never looked at an electronics schematic either. This easy tutorial was really helpful. I figured out that the 6 and 7 bits on the second 555 timer needed to be connected all by myself.
really nice!
Here's a video of my pocket theremin:
http://www.youtube.com/watch?v=12PJSEqqCkY

This is my first project and my first foray into DIY electronics, so I have a question or two. The whole project, including the speaker is very warm. Is this normal or did I miss a wire?

should i have used a linear pot, i put a logarithmic pot in as it is controlling a speaker but tone is very quiet until pot is turned right up. the LDR's i used are rated 5-10k light resistance, would higher resistance ones be better. 555 number 2 should have pins 6&7 tied

this is an excellent project for newbie diyers

im brand new to this stuff and i built it on to a solderless breadboard with no problem. (dont know ho to solder yet)
and i even incorprated a little switch and an led indicator light to test the connection.

whether you use the box as described in the article or a breadboard (i recommend the breadboard.)this is a great project.

and remember.. say no to envorinmental extremeism :-)

this is an excellent project for newbie diyers

im brand new to this stuff and i built it on to a solderless breadboard with no problem. (dont know ho to solder yet)
and i even incorprated a little switch and an led indicator light to test the connection.

whether you use the box as described in the article or a breadboard (i recommend the breadboard.)this is a great project. i ended up twisting the capacitor leads and broke them so i had to trash them but aside from that it was great.

and remember.. say no to envorinmental extremeism :-)

this is an excellent project for newbie diyers

im brand new to this stuff and i built it on to a solderless breadboard with no problem. (dont know ho to solder yet)
and i even incorprated a little switch and an led indicator light to test the connection.

whether you use the box as described in the article or a breadboard (i recommend the breadboard.)this is a great project.

and remember.. say no to envorinmental extremeism :-)

Could anybody who built a working specimen (preferably Soulrep) tell me what specific kind of photocell they used? 'Cause they come in different ranges of resistance and I don't want to suffocate the whole circuit with too much resistance.

well i first saw a theremin while watching he song remains the same when jimmy page puts down his guitar and moves his hand over a strange black box with an antenna and made really strange scifi sounds i was hooked

i scoured the internet trying to find plans and i stumbled here. and yes i successfully built it and i got to say mine sounded better than the recording although it is i a little high pitched (kind of like a dental drill) but if you dim the lights it sounds much better.

for photo cells i just used any random ones i got from the local radioshack. in fact i got everything from radioshack i don't know why all of you guys sit around waiting for parts just go to the damn store and buy them.

the 555 chip is installed with the prongs down and i believe there is a mark in it to tell you which is the top. i referred to the paper that came in the package if my chip

and the 6&7 are tied

i also found it helpful to use a bigger box that you can fit the battery in i also added a simple switch on the positive lead of the battery to turn it on and off and a 1/4 inch mono jack in series with the speaker (so that i can plug it in to my guitar amp) in such a way so that when it is plugged in the speaker turns off.

and for the record i never actually built any thing be for this and never used a bread board and the only things i have built are simple on/off and volume switches for my guitar and a $3 contact mic for my mandolin. and i used a cheap $7 soldering iron

but as far as orientation of my 555 chip i think i just might have gotten lucky.

as far as being eco friendly, when the time comes i will be sure to dispose if it properly at the nearest hazardous waste treatment plant.

does anyone know where to get the uF .01 capacitor? the link doesn't work.

also, most of the links here dont work. send me all of the info that you can please.

@ jacob.musil: I used some random photocells (don't remember which specs). They're very cheap, so just get a nice selection and build the whole circuit on a breadboard so you can test them. then solder the ones you like best.

that is a very great information and tips

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