Title: I'm determined to build a theremin.
Post by: erdabyz on December 16, 2012, 09:24:31 pm
Post by: erdabyz on December 16, 2012, 09:24:31 pm
Hi folks,
My girlfriend is a musician (well, for now she's a student) and some days ago she came to me saying that a teacher had told the class about some weird electronic instrument that you played without touching it and that was used to make alien sounds for movies. Being the electronics freak I am I automatically knew she was talking about a theremin. She was quite fascinated with it and told me she would like to try one.
So her birthday is relatively near and I'm determined to build her one as a present. But I wanted it to be a true theremin, fully analog, with all its LC oscillating glory... so I searched a bit and found this:
http://www.suonoelettronico.com/downloa ... herwav.pdf (http://www.suonoelettronico.com/downloads/HotRodEtherwav.pdf)
That has an schematic which uses mostly modern components and that uses transconductance amplifiers which should emulate the original valves quite well. Actually that's the schematic of a kit that some folks sell for 400 bucks so you can make your own professional theremin. I also found the schematic it derives from:
http://wiki.joanillo.org/images/a/a0/EMTheremin.pdf (http://wiki.joanillo.org/images/a/a0/EMTheremin.pdf)
which has some info about the required inductors and that.
Finding the components was a pain in the ass. Virtually no distributor sells adjustable inductors anymore, and high-Q fixed inductors of over 10uH are also hard to find nowadays. Finally found some TOKO FDSV series adjustable inductors and some relatively high Q fixed inductors at RS components. And surprisingly they were SMD (hooray!). Ordered them ASAP. Also surprisingly the 10, 5 and 2.5mH chokes required for the antennas (BOURNS 6300 series) were available everywhere at a price I'd never imagined. I was expecting 5 bucks per coil but they are just 1,35€ each.
Next I ordered everything else from digikey. I have chosen quite premium components. Capacitors related to audio are either tantalum or poliphenylene sulphide film capacitors which are quite expensive but that way audiophiles won't say it sounds bad because my capacitors haven't got enough magic powder inside them. Also there are only a few caps that need to be this good and this is a present for someone I love beyond money so... I also threw in some 10uF 16V 0805 X5R capacitors for decoupling pourposes that weren't in the original schematic but that I think they should be neccesary. 100nF's wouldn't do shit in this design as they have large impedances at the frequencies involved in the circuit. All the other caps are also high quality ceramics or similar but those run for pretty cheap.
LM13600M's were found on ebay.
I decided that unlike in the original desing i'd try to make the board as short as possible and assemble the RF chokes for the antennas in series and in line inside a plastic tube instead of mounting them in the board (well, I have to mount one in the board because of the way it is connected but the rest will be outside). That should improve the way the inductors couple to act like a single but "distributed" inductor with reduced parasitic capacitance and such things.
Next stage: design the PCB. I love squeezing circuits in tight layouts but having in mind a couple of good layout rules. I'm pretty happy with the result. It still needs a bit of touching and I've used overly large trace thicknesses just because and because I could. It's meant to be mounted upside down (the wooden case will have three holes in the bottom that align with the tunable coil's screws so I can tune the thing) and have the large 2200uF caps mounted at right angle. I have to correct that silkscreen, for example.
I'll try to finish the board this christmas and maybe populate one just for testing. The wooden box, the front panel an everything else will be made after I finish my finals.
Here's the current board and schematic. I hate doing schematics so forgive me for the lack of cleanliness... The board is much better done.
I may give away some of the boards when they're done if any of you also wants a theremin.
[attachment=0]
My girlfriend is a musician (well, for now she's a student) and some days ago she came to me saying that a teacher had told the class about some weird electronic instrument that you played without touching it and that was used to make alien sounds for movies. Being the electronics freak I am I automatically knew she was talking about a theremin. She was quite fascinated with it and told me she would like to try one.
So her birthday is relatively near and I'm determined to build her one as a present. But I wanted it to be a true theremin, fully analog, with all its LC oscillating glory... so I searched a bit and found this:
http://www.suonoelettronico.com/downloa ... herwav.pdf (http://www.suonoelettronico.com/downloads/HotRodEtherwav.pdf)
That has an schematic which uses mostly modern components and that uses transconductance amplifiers which should emulate the original valves quite well. Actually that's the schematic of a kit that some folks sell for 400 bucks so you can make your own professional theremin. I also found the schematic it derives from:
http://wiki.joanillo.org/images/a/a0/EMTheremin.pdf (http://wiki.joanillo.org/images/a/a0/EMTheremin.pdf)
which has some info about the required inductors and that.
Finding the components was a pain in the ass. Virtually no distributor sells adjustable inductors anymore, and high-Q fixed inductors of over 10uH are also hard to find nowadays. Finally found some TOKO FDSV series adjustable inductors and some relatively high Q fixed inductors at RS components. And surprisingly they were SMD (hooray!). Ordered them ASAP. Also surprisingly the 10, 5 and 2.5mH chokes required for the antennas (BOURNS 6300 series) were available everywhere at a price I'd never imagined. I was expecting 5 bucks per coil but they are just 1,35€ each.
Next I ordered everything else from digikey. I have chosen quite premium components. Capacitors related to audio are either tantalum or poliphenylene sulphide film capacitors which are quite expensive but that way audiophiles won't say it sounds bad because my capacitors haven't got enough magic powder inside them. Also there are only a few caps that need to be this good and this is a present for someone I love beyond money so... I also threw in some 10uF 16V 0805 X5R capacitors for decoupling pourposes that weren't in the original schematic but that I think they should be neccesary. 100nF's wouldn't do shit in this design as they have large impedances at the frequencies involved in the circuit. All the other caps are also high quality ceramics or similar but those run for pretty cheap.
LM13600M's were found on ebay.
I decided that unlike in the original desing i'd try to make the board as short as possible and assemble the RF chokes for the antennas in series and in line inside a plastic tube instead of mounting them in the board (well, I have to mount one in the board because of the way it is connected but the rest will be outside). That should improve the way the inductors couple to act like a single but "distributed" inductor with reduced parasitic capacitance and such things.
Next stage: design the PCB. I love squeezing circuits in tight layouts but having in mind a couple of good layout rules. I'm pretty happy with the result. It still needs a bit of touching and I've used overly large trace thicknesses just because and because I could. It's meant to be mounted upside down (the wooden case will have three holes in the bottom that align with the tunable coil's screws so I can tune the thing) and have the large 2200uF caps mounted at right angle. I have to correct that silkscreen, for example.
I'll try to finish the board this christmas and maybe populate one just for testing. The wooden box, the front panel an everything else will be made after I finish my finals.
Here's the current board and schematic. I hate doing schematics so forgive me for the lack of cleanliness... The board is much better done.
I may give away some of the boards when they're done if any of you also wants a theremin.
[attachment=0]
Title: Re: I'm determined to build a theremin.
Post by: ian on December 20, 2012, 08:32:33 am
Post by: ian on December 20, 2012, 08:32:33 am
Great writeup! I have always wanted to make a theremin, but besides learning to play the Dr. Who theme I have no idea what I would do with it :)
Looking forward to pics and hearing how it turns out.
Looking forward to pics and hearing how it turns out.
Title: Re: I'm determined to build a theremin.
Post by: erdabyz on December 26, 2012, 05:34:44 pm
Post by: erdabyz on December 26, 2012, 05:34:44 pm
PCB is finished and sent to SEEED. As it costs the same to get 10 10x5 boards and 10 10x10 boards I panelized another design (a geiger counter) to fill a 10x10 board.
The geiger counter is based on mightyohm's design. I don't really like the PSU design but this has just been a quick design to fill the extra space and to test a geiger tube I got some time ago so I didn't wanted to think.
Here are the files:
[attachment=0]
I will post full components list and maybe give some of the PCB's away when they arrive and the first prototype gets assembled. I don't want anyone to try and build this before being sure that it works as intended.
The geiger counter is based on mightyohm's design. I don't really like the PSU design but this has just been a quick design to fill the extra space and to test a geiger tube I got some time ago so I didn't wanted to think.
Here are the files:
[attachment=0]
I will post full components list and maybe give some of the PCB's away when they arrive and the first prototype gets assembled. I don't want anyone to try and build this before being sure that it works as intended.
Title: Re: I'm determined to build a theremin.
Post by: ludowique on December 27, 2012, 10:30:24 pm
Post by: ludowique on December 27, 2012, 10:30:24 pm
[quote author="erdabyz"]Hi folks,
I may give away some of the boards when they're done if any of you also wants a theremin.
[/quote]
building a theremin was a project years ago. but i stumble on the lack of time. i saw your post via the twitter channel.
will you send one of the Boards to Berlin, Germany?
Thanks!
I may give away some of the boards when they're done if any of you also wants a theremin.
[/quote]
building a theremin was a project years ago. but i stumble on the lack of time. i saw your post via the twitter channel.
will you send one of the Boards to Berlin, Germany?
Thanks!
Title: Re: I'm determined to build a theremin.
Post by: erdabyz on December 28, 2012, 01:29:46 am
Post by: erdabyz on December 28, 2012, 01:29:46 am
[quote author="ludowique"][quote author="erdabyz"]Hi folks,
I may give away some of the boards when they're done if any of you also wants a theremin.
[/quote]
building a theremin was a project years ago. but i stumble on the lack of time. i saw your post via the twitter channel.
will you send one of the Boards to Berlin, Germany?
Thanks![/quote]
Yeah, sure. When mine is built and the PCB is tested I'll send you one if you want, and I'll also post the final partslist with some notes on where to get the components. You should be able to get every component in germany, as long as RS components is available there.
I may give away some of the boards when they're done if any of you also wants a theremin.
[/quote]
building a theremin was a project years ago. but i stumble on the lack of time. i saw your post via the twitter channel.
will you send one of the Boards to Berlin, Germany?
Thanks![/quote]
Yeah, sure. When mine is built and the PCB is tested I'll send you one if you want, and I'll also post the final partslist with some notes on where to get the components. You should be able to get every component in germany, as long as RS components is available there.
Title: Re: I'm determined to build a theremin.
Post by: ludowique on December 28, 2012, 08:51:05 am
Post by: ludowique on December 28, 2012, 08:51:05 am
[quote author="erdabyz"][quote author="ludowique"][quote author="erdabyz"]Hi folks,
I may give away some of the boards when they're done if any of you also wants a theremin.
[/quote]
building a theremin was a project years ago. but i stumble on the lack of time. i saw your post via the twitter channel.
will you send one of the Boards to Berlin, Germany?
Thanks![/quote]
Yeah, sure. When mine is built and the PCB is tested I'll send you one if you want, and I'll also post the final partslist with some notes on where to get the components. You should be able to get every component in germany, as long as RS components is available there.[/quote]
Well there is reichelt.de and segor.de. Segor is my great hope - it is a little Shop here in Berlin, and till now they got *everything* i want. Just to be sure: those "RS components" are the adjustable Inductors you wrote about in your first post, right? And if you have parts left over - i know where you can get rid of them. ;)
I may give away some of the boards when they're done if any of you also wants a theremin.
[/quote]
building a theremin was a project years ago. but i stumble on the lack of time. i saw your post via the twitter channel.
will you send one of the Boards to Berlin, Germany?
Thanks![/quote]
Yeah, sure. When mine is built and the PCB is tested I'll send you one if you want, and I'll also post the final partslist with some notes on where to get the components. You should be able to get every component in germany, as long as RS components is available there.[/quote]
Well there is reichelt.de and segor.de. Segor is my great hope - it is a little Shop here in Berlin, and till now they got *everything* i want. Just to be sure: those "RS components" are the adjustable Inductors you wrote about in your first post, right? And if you have parts left over - i know where you can get rid of them. ;)
Title: Re: I'm determined to build a theremin.
Post by: 4dolfin on December 28, 2012, 05:22:04 pm
Post by: 4dolfin on December 28, 2012, 05:22:04 pm
I tried to buld one from a kit fron Paia. No matter what I did I could never get the volume antenna to work. This was about 15 years ago. Since then I've been itchin to get one to play. I was thinking of getting the kit from Moog and putting it together. But I think this would be more rewarding. I can't wait to see and hear your project when it is complete. Also I would love to get one of these PCBs as well.
Title: Re: I'm determined to build a theremin.
Post by: todro on December 30, 2012, 05:19:12 pm
Post by: todro on December 30, 2012, 05:19:12 pm
Sounds like an interesting project. Saw this instrument first at a Jean Michel Jarre Concert and was really surprised...
If you have a spare pcb available, I'd would be interested too :-)
Thanks for sharing the project.
Greetings,
Torsten
If you have a spare pcb available, I'd would be interested too :-)
Thanks for sharing the project.
Greetings,
Torsten
Title: Re: I'm determined to build a theremin.
Post by: erdabyz on January 10, 2013, 05:16:21 pm
Post by: erdabyz on January 10, 2013, 05:16:21 pm
Boards are here. Stay tuned!
(http://http://imgur.com/yLcvo)
(http://http://imgur.com/yLcvo)
Title: Re: I'm determined to build a theremin.
Post by: erdabyz on January 19, 2013, 03:27:26 pm
Post by: erdabyz on January 19, 2013, 03:27:26 pm
Partially assembled board:
(http://http://imgur.com/ipfgUuZ)
It needs to be ultrasonically cleaned, but that will be done after it's fully assembled.
Damn I have too many components. It has taken me much longer than I expected to assemble this because I have to search the components in a way too large pile...8 full boxes and counting...
(http://http://imgur.com/ipfgUuZ)It needs to be ultrasonically cleaned, but that will be done after it's fully assembled.
Damn I have too many components. It has taken me much longer than I expected to assemble this because I have to search the components in a way too large pile...8 full boxes and counting...
Title: Re: I'm determined to build a theremin.
Post by: ludowique on January 20, 2013, 05:22:39 pm
Post by: ludowique on January 20, 2013, 05:22:39 pm
cant wait to build it too. ;) it looks great!
Title: Re: I'm determined to build a theremin.
Post by: erdabyz on January 21, 2013, 11:16:18 am
Post by: erdabyz on January 21, 2013, 11:16:18 am
[quote author="ludowique"]cant wait to build it too. ;) it looks great![/quote]
My finals period ends february 4th. Then I'll have a spare week to finish this project. Hopefully I'll be able to test the board earlier, and if it works I'll send you one of the spares.
My finals period ends february 4th. Then I'll have a spare week to finish this project. Hopefully I'll be able to test the board earlier, and if it works I'll send you one of the spares.
Title: Re: I'm determined to build a theremin.
Post by: todro on January 21, 2013, 10:01:50 pm
Post by: todro on January 21, 2013, 10:01:50 pm
Great to see the project's progress
Title: Re: I'm determined to build a theremin.
Post by: Sleepwalker3 on January 22, 2013, 06:05:44 am
Post by: Sleepwalker3 on January 22, 2013, 06:05:44 am
Pity I hadn't caught onto this a bit earlier, might have saved you a lot of searching for parts. Australian Electronics Magazine 'Silicon Chip' did a project for this years ago and later did a Mark II version, it's still available as a kit from Aussie Electronics place 'Jaycar Electronics'.
The Silicon chip articles can be found through here -
http://http://www.google.com.au/#hl=en&tbo=d&spell=1&q=theremin+site:siliconchip.com.au&sa=X&ei=ABz-UJ2PAaPniAeivYC4DA&ved=0CCwQvwUoAA&bav=on.2,or.r_gc.r_pw.r_qf.&bvm=bv.41248874,d.dGY&fp=b987864691354c7e&biw=1280&bih=642
and the kit can be found here for $75 Australian (roughly the same as $USD)
http://http://www.jaycar.com.au/productView.asp?ID=KC5475
Silicon Chip only allow you to see a part of their article without payment, but the kits come with full printed details.
The Silicon chip articles can be found through here -
http://http://www.google.com.au/#hl=en&tbo=d&spell=1&q=theremin+site:siliconchip.com.au&sa=X&ei=ABz-UJ2PAaPniAeivYC4DA&ved=0CCwQvwUoAA&bav=on.2,or.r_gc.r_pw.r_qf.&bvm=bv.41248874,d.dGY&fp=b987864691354c7e&biw=1280&bih=642
and the kit can be found here for $75 Australian (roughly the same as $USD)
http://http://www.jaycar.com.au/productView.asp?ID=KC5475
Silicon Chip only allow you to see a part of their article without payment, but the kits come with full printed details.
Title: Re: I'm determined to build a theremin.
Post by: Sleepwalker3 on January 22, 2013, 06:09:29 am
Post by: Sleepwalker3 on January 22, 2013, 06:09:29 am
A pic
Title: Re: I'm determined to build a theremin.
Post by: erdabyz on January 26, 2013, 03:52:33 pm
Post by: erdabyz on January 26, 2013, 03:52:33 pm
Today I made a 3D sketchup drawing of the theremin antennas. I wanted the volume antenna to look like etherwave's one, and not to be a simple hairpin bend of tube. I found a picture of both of the etherwave antennas and knowing that the pitch one is just a 18" long tube I roughly derived the measurements of the volume antenna using a picture ruler and scaling. I rounded my measurements to the closest inch and I think I got a pretty accurate drawing. I'll get them manufactured next week. Stay tuned.
Title: Re: I'm determined to build a theremin.
Post by: presslab on January 27, 2013, 08:13:31 pm
Post by: presslab on January 27, 2013, 08:13:31 pm
Nice job on your PCB! Looking forward to what comes next.
Could you make the antenna yourself with some stainless tubing from McMaster-Carr and a spring tubing bender?
Could you make the antenna yourself with some stainless tubing from McMaster-Carr and a spring tubing bender?
Title: Re: I'm determined to build a theremin.
Post by: erdabyz on January 28, 2013, 12:45:37 am
Post by: erdabyz on January 28, 2013, 12:45:37 am
[quote author="presslab"]Nice job on your PCB! Looking forward to what comes next.
Could you make the antenna yourself with some stainless tubing from McMaster-Carr and a spring tubing bender?[/quote]
No McMaster-Carr in Spain xD. My antennas will be made out of chrome-plated copper tube or stainless steel, whatever is cheaper. I'd prefer copper because that way I could easily solder the wires to them. My father works at a factory where they make metal parts and they have the required tools, so I've given him the drawings and they'll hopefully be done by next week. I'll also get the required compression fittings to fit the antennas to the wooden case.
I finish my finals on 4th february and I'll have a whole holidays week then. I'll hopefully finish the project in that week.
Could you make the antenna yourself with some stainless tubing from McMaster-Carr and a spring tubing bender?[/quote]
No McMaster-Carr in Spain xD. My antennas will be made out of chrome-plated copper tube or stainless steel, whatever is cheaper. I'd prefer copper because that way I could easily solder the wires to them. My father works at a factory where they make metal parts and they have the required tools, so I've given him the drawings and they'll hopefully be done by next week. I'll also get the required compression fittings to fit the antennas to the wooden case.
I finish my finals on 4th february and I'll have a whole holidays week then. I'll hopefully finish the project in that week.
Title: Re: I'm determined to build a theremin.
Post by: presslab on January 28, 2013, 01:34:46 am
Post by: presslab on January 28, 2013, 01:34:46 am
I used the world's largest hardware store just as an example, although you could certainly order from them. :) If you can chrome them, I think that would be the nicest looking, and it looks like the Etherwave has chromed antennas too. I suppose having your father build them is almost as good as doing it yourself. :)
Title: Re: I'm determined to build a theremin.
Post by: erdabyz on February 02, 2013, 09:50:01 pm
Post by: erdabyz on February 02, 2013, 09:50:01 pm
Update:
In this week I have done a couple of things in my spare time between hours of study. I'll have my last final this monday and then I'll be free for a week and things will speed up a lot.
The antennas are almost done. I'm getting a set made of chromed copper and a set made of chromed steel. The chromed steel tubing that was available was 12mm wide, maybe too much, so I'll probably use the copper ones. The volume antennas are already done, but the copper pitch antenna still needs some straightening because the copper tube came in a roll, and that requires a special tool. They'll probably be finished this sunday and I'll post pics.
The wooden case is mostly designed. I have it 3d modelled in sketchup and I'll assemble it next week. The aluminium front plate will have to wait a bit but I'll mount the components somehow to make a test run.
I soldered the remaining through-hole components in the PCB and made the coil "sausages" for both antennas. Here's a picture of it:
(http://http://imgur.com/ZZBKSkT)
In this week I have done a couple of things in my spare time between hours of study. I'll have my last final this monday and then I'll be free for a week and things will speed up a lot.
The antennas are almost done. I'm getting a set made of chromed copper and a set made of chromed steel. The chromed steel tubing that was available was 12mm wide, maybe too much, so I'll probably use the copper ones. The volume antennas are already done, but the copper pitch antenna still needs some straightening because the copper tube came in a roll, and that requires a special tool. They'll probably be finished this sunday and I'll post pics.
The wooden case is mostly designed. I have it 3d modelled in sketchup and I'll assemble it next week. The aluminium front plate will have to wait a bit but I'll mount the components somehow to make a test run.
I soldered the remaining through-hole components in the PCB and made the coil "sausages" for both antennas. Here's a picture of it:
(http://http://imgur.com/ZZBKSkT)
Title: Re: I'm determined to build a theremin.
Post by: erdabyz on February 04, 2013, 12:45:44 am
Post by: erdabyz on February 04, 2013, 12:45:44 am
As promised, here are the antennas:
(http://http://imgur.com/56pvTVe)
I got two volume antennas made because the first one wasn't perfect enough for my father's standars. Unfortunately that tube isn't made for such bends and some of the chrome plating has scorched, and the tube has some markings on it (diameter, material, type of tube and all that stuff). Anyways, i'm more than happy with the result and maybe in the future I'll get some chrome paint and make them perfect, but they are good as they are and the shape is just perfect. They are longer than they should because I'll have to tune the thing and they'll require adjustments, so better to have extra material than to be short.
I also show the two compression fittings for the volume antenna.
Also turns out that this copper is solid enough so I won't have to fill them with rosin.
(http://http://imgur.com/56pvTVe)I got two volume antennas made because the first one wasn't perfect enough for my father's standars. Unfortunately that tube isn't made for such bends and some of the chrome plating has scorched, and the tube has some markings on it (diameter, material, type of tube and all that stuff). Anyways, i'm more than happy with the result and maybe in the future I'll get some chrome paint and make them perfect, but they are good as they are and the shape is just perfect. They are longer than they should because I'll have to tune the thing and they'll require adjustments, so better to have extra material than to be short.
I also show the two compression fittings for the volume antenna.
Also turns out that this copper is solid enough so I won't have to fill them with rosin.
Title: Re: I'm determined to build a theremin.
Post by: todro on February 04, 2013, 01:18:06 am
Post by: todro on February 04, 2013, 01:18:06 am
Looks great, eagerly awaiting the final product. Great job!
Title: Re: I'm determined to build a theremin.
Post by: ian on February 04, 2013, 03:37:30 pm
Post by: ian on February 04, 2013, 03:37:30 pm
Nice work, thanks for the update!
Title: Re: I'm determined to build a theremin.
Post by: erdabyz on February 06, 2013, 09:31:19 pm
Post by: erdabyz on February 06, 2013, 09:31:19 pm
So today I got good news and bad news.
Good news: EVERYTHING WORKS. Every potentiometer does what it's supposed to do, the oscillators oscillate, the thing sounds and it's sensitive to my hands
Bad news: tuning the thing is a pain in the ass.Well, tuning the volume antenna is a pain in the ass. I can only get it to sound if I load the circuit with the probe of my o-scope in the middle of the coil sausage and leave the volume antenna unconnected, using the compression fitting as the antenna. No matter how much I adjust the coil, it simply doesn't get in resonance. Also the oscillating frequency is a bit too high, I get about 550-600kHz where I should be getting 450kHz. I think that is the problem. Maybe going SMD and having much less parasitic capacitance between components is what's happening here.
Who knows, I'll try and make some simulations to understand what I'm seeing and probably I'll have to order moar capacitors to get the thing going.
At least now I know it works, so those who wanted a PCB please PM me with address and that.
Good news: EVERYTHING WORKS. Every potentiometer does what it's supposed to do, the oscillators oscillate, the thing sounds and it's sensitive to my hands
Bad news: tuning the thing is a pain in the ass.Well, tuning the volume antenna is a pain in the ass. I can only get it to sound if I load the circuit with the probe of my o-scope in the middle of the coil sausage and leave the volume antenna unconnected, using the compression fitting as the antenna. No matter how much I adjust the coil, it simply doesn't get in resonance. Also the oscillating frequency is a bit too high, I get about 550-600kHz where I should be getting 450kHz. I think that is the problem. Maybe going SMD and having much less parasitic capacitance between components is what's happening here.
Who knows, I'll try and make some simulations to understand what I'm seeing and probably I'll have to order moar capacitors to get the thing going.
At least now I know it works, so those who wanted a PCB please PM me with address and that.
Title: Re: I'm determined to build a theremin.
Post by: erdabyz on February 07, 2013, 06:40:24 pm
Post by: erdabyz on February 07, 2013, 06:40:24 pm
I'm almost there. I got the volume antenna to work just right if I load the circuit with my scope, and to somewhat work without load. For that I've had to almost double the capacitance in the volume oscillator and to more than double the inductance. It's weird because the oscillating frequency doesn't get reduced too much with these changes... now I got it at about 400kHz
Title: Re: I'm determined to build a theremin.
Post by: ian on February 13, 2013, 05:33:55 pm
Post by: ian on February 13, 2013, 05:33:55 pm
Nice work! Excited to see it going. Any chance of a quick video?
Title: Re: I'm determined to build a theremin.
Post by: j0hnth0m on February 19, 2013, 07:45:24 pm
Post by: j0hnth0m on February 19, 2013, 07:45:24 pm
I curious about your schematic. Earlier you referenced the EMTheremin article and also the Hotrodding article. The latter article has an updated schematic with a few key changes to the original design. Which version did you base your design upon? Were there any significant departures from the original design you care to share? I was very interested in your comments regarding capacitor selection but failed to completely grasp which capacitors you where upgrading.
I am actually also starting down this same path but don't have nearly the experience you obviously do so I'm trying to glean as much from you posting as possible.
Thanks.
I am actually also starting down this same path but don't have nearly the experience you obviously do so I'm trying to glean as much from you posting as possible.
Thanks.
Title: Re: I'm determined to build a theremin.
Post by: erdabyz on February 22, 2013, 11:48:42 pm
Post by: erdabyz on February 22, 2013, 11:48:42 pm
[quote author="j0hnth0m"]I curious about your schematic. Earlier you referenced the EMTheremin article and also the Hotrodding article. The latter article has an updated schematic with a few key changes to the original design. Which version did you base your design upon? Were there any significant departures from the original design you care to share? I was very interested in your comments regarding capacitor selection but failed to completely grasp which capacitors you where upgrading.
I am actually also starting down this same path but don't have nearly the experience you obviously do so I'm trying to glean as much from you posting as possible.
Thanks.[/quote]
Right now my pitch antenna is completely out of tune and the volume one can't be completely tuned. I ran out of capacitors so I made a new order with more values to try out. They arrived yesterday, I hope I can do more testing this weekend and finally get it properly going.
I'll post final schematics and things when i get it fully working. I'm not sure about why is there such a mismatch between the original design and mine....
I am actually also starting down this same path but don't have nearly the experience you obviously do so I'm trying to glean as much from you posting as possible.
Thanks.[/quote]
Right now my pitch antenna is completely out of tune and the volume one can't be completely tuned. I ran out of capacitors so I made a new order with more values to try out. They arrived yesterday, I hope I can do more testing this weekend and finally get it properly going.
I'll post final schematics and things when i get it fully working. I'm not sure about why is there such a mismatch between the original design and mine....