D-Beam controller

[Guest Ryan]

hi! im a newbie and i dont have too much experience in electronics.

I was wondering if someone can help me with this:

http://www.geocities.com/robobix/Dbeam.html

This page contains schematics for a d beam distance measurement circuit. I know that any analog device that has an output range of 0-5v can be used... problem is, i dont know the voltage output range for this circuit. Im planning to add it do a MIDIplus box im planning to build.

Also, i dont know what IR emmiter/receptor to use.

Hope someone can help me...

thanks

Ryan

[TK.]

Hi Ryan,

this circuit is not perfect for adapting it to a PIC, you need a second power supply, and the output voltage range is from 0 to 12V.

In fact a digitally controlled D-Beam could be realized on a very easy way, it could run as background task in a MIOS application. I will evaluate this in the next days (a D-Beam would be a nice feature for my MIDIbox SID :-) )

Best Regards, Thorsten.

[TK.]

Ok, here a description how it could work:

I used an IR sensor with integrated amplifier of an old TV (such sensors can be found in most consumer products) and the IR LED of an old remote control. The IR LED is switched with a constant frequency.

And here the results from the scope:

(Channel 1: IR Input, Channel 2: IR Output)

Than shorter the distance between my hand and the IR sensor/LED pair, than more pulses are received. So, the only thing which has to be done by the PIC is to count the pulses in order to measure the distance.

This could be done by a seperate - small - PIC device (Hi Duggle, are you reading this? This would be a nice IIC gadget) or by MIOS projects which still have a free counter input ( Pin C.1 or C.2)

Best Regards, Thorsten.

[Guest Zzzz...]

Hi,

Would this also work with some old mice with a PS-2 connection,

which have two  IR-transmitter and a receiver and between this the mechanical part (ie looks like a fan (don't know the exact word)).

Or is the range for these Ir's too short, or does it really have to be a remote control from a old tv ....

Just a question...just being curieus...

Thanks in advance...

Erik

/EDIT: Sorry, didn't read there was also a integrated amplifier at the remote control....that will do the difference...

Sorry, for bothering.

[Guest Ryan]

Thanks a lot Thorsten!

Sorry i had to bother you with the email, i figured out the login problem already :)

I'm looking forward to the d beam controller plans, i can test it for you once i finish my box. also, i appreciate u not using a hard to find component for the IR's (i can just rip out an old tv set :)), getting my hand on the parts are proving to be a bit hard.

Regards,

Ryan

[TK.]

Some bad news: the counter values are jittering (independent from the frequency ), jitter stops with 4-bit resolution, so that w/o a sophisticated interpolation algorithm the d-beam implementation is useless for a musical application. The programming of such an algorithm isn't trivial and consumes a lot of time & effort.

I also tried another IR-sensor and the output signal is completely different (it sends pulses with a constant frequency of 1kHz - very strange).

This means that unfortunately not all types of IR sensors with integrated amplifier can be re-used, different ones have to be tried. This will be very difficult for peoeple who don't own a scope.

So in fact this approach won't really help, I cannot give you any spec for the IR sensor (I only know that it's from a TV which I've canibalized ca. 20 years ago ;-)) and I've currently no motivation to search for a perfect algorithm for my own sensor (the advantage of a D-Beam isn't really so big, it would be a nice feature but nothing else...)

So - thats all from my side ;-)

Best Regards, Thorsten.

[Duggle]

Hi Thorsten,others,

Yes, I think what youve observed is the fact that signal coupling deteriorates with distance, not a good means of distance measurement!

I'm sure there are some very effective ways of doing this (measuring distance) that are easy to implement.

To the original poster, Ryan, what is your interest in this? If it is oriented to a musical instrument type controller have a look (via google) at Theremin (spelling?).

Such instruments could be interfaced to midibox using frequency to voltage coverter IC's for pitch and amplitude detectors for velocity. Post back if you find something interesting as this is something I have thought about in the past.

Also a  highly accurate determination of pitch can be achieved using the onboard PIC CCP modules (upt o 16 bit accuracy,2 channels).

cheers

[Guest Ryan]

Hi duggle!

    I have been reading about theremins. My purpose for this is to be able to to control parameters on my soft synths using hand motion... yup! a theremin would be good. I was reading about this one project that doesnt require tubes, just coils which you can easily wind by yourself.

     It looks promising, its definitely better than a          d-beam because the theremin can control two parameters with one hand via the x and y axes (imagine assigning the x axis to pan and cutoff on the y axis)... or maybe an x,y,z axis is possible, i dont know yet, focus a few lights on your hands and watch the crowd wonder what the hell you're doin'! hehe its gonna be a crowd pleaser huh? :)

    One little problem thou... i dont know hi to interface it with the midibox. You mentioned frequency to voltage converter IC's... What would you suggest? I'd really appreciate a schematic on this... if you have the time. I would be happy to build a prototype and test it.

Thanks a lot!

Ryan

[Duggle]

Hi Ryan,

I'm maxed out completing another midibox design project so I can only help with the broad approach.

Some basic electronic interfacing/diagnostic skill is required.

1) keep looking for theremin projects (when I last looked there were very many!) Some will be much easier to build than others. Find the easiest (to start with)

2)  Theremin outputs an audiowave of varying freq and amplitude. If you dont want huge accuracy for pitch (what you described) devise a FV circuit that outputs a DC voltage of 0-5V (using LM2907?), [There are hobby kits that use a low cost FV converter IC this is where I would look first, in choosing a device]

For amplitude a level detector/recitifer with max output of 5V (using common op amp).

Like I said, electronic skills are required, however a very elegant, low cost implementation is absolutly do-able!

cheers

[Guest Ryan]

Hi Duggle,

   I like i said, my knowledge in electronics is very limited, I'm a medical student!:) I'm not supposed to know all these stuff, but I'll try anyways... I think I can get help from my engineer friends(or maybe somebody else from the forum could help). I'll keep you guys posted on this

Regards,

Ryan

[Guest Ryan]

Duggle! I found a schematic for a digital theremin, one that gives a DC output... isn't this nice?

http://www.maxiespages.com/images/Theremin/Glasgow-digital.gif

and another one here

http://www.maxiespages.com/images/Theremin/simple.jpg

[Guest tew]

I'm looking into an IR distance-detecting element for my MIOS project.  The part I'm looking at is a Fairchild Electronics QRD1114, a reflective object sensor.  Here's a relevant diagram from the datasheet:

These distances are measured in mils, which is 1/1000th of an inch, so we're looking at detecting distances between .6 and 6 mm.  Not so much, but decent.  $0.90USD each (digikey).

I'm looking at adding an IR LED nearby these guys to increase the amount of radiation they'd be getting, which ought to skew the curve a little.

[Wancho]

Hi everybody! I'm working in my midibox but it isn´t  finalized yet! My design use a IR sensor like D-Beam. I want to use a Sharp GP2D12. I will do lots of experiments for you. I hope I help you! Ciao!

[Guest Ryan]

tew,

     yup! skewing the curve a little would be real good coz if i understand it right... with this curve it would detect very slight hand movements which would make it hard to control. Thank  man! tell me if there's anything i can do to help u with experimenting:)

regards,

Ryan

[Guest Ryan]

Hi wancho!

  Thanks for the interest in this. If there's anything i can do to help, drop me a line

regards,

Ryan

[Guest tew]

skewing the curve a little would be real good coz if i understand it right... with this curve it would detect very slight hand movements which would make it hard to control.

Yeah, I have my concerns about the sensitivity.  I may end up using the parts as no-touch buttons, since the on-off status would be easier to deal with than the distance-related voltage.

[admir]

Hi all, sorry for jumping in... may I suggest a different approach? Forget IR, use ultrasound. Here you have schematics and PIC asm example:

http://www.robot-electronics.co.uk/htm/srf04tech.htm

Regards,

Admir.

[Guest tew]

Forget IR, use ultrasound.

I've thought about that for my project, but I'm interested in building something to detect a strumming hand motion.  I'm hoping to have 4 or 6 sensors in a line, and "strum" the box from a distance of no more than 3 inches.  Ideally, I'd like to be able to detect both distance and velocity.  I'm planning to map hand distance onto volume, and each sensor will control a different note of a chord, so I should (in theory) have a lot of control over the arpeggiation.

For my purposes, ultrasound is overkill, since I'm dealing with such a short distance.  Also, ultrasound is too expensive for me to use more than one.

[DrBunsen]

    I have been reading about theremins. My purpose for this is to be able to to control parameters on my soft synths using hand motion... yup! a theremin would be good.

You might want to have a look at the PAiA Theremax, a relatively cheap kit theremin that has CV (control voltage) outputs for pitch, volume, velocity, and gate/trigger.  These should be easy to add to a MIDIbox through an AIN module.

http://www.paia.com/theremax.htm

[Guest blafferen]

(You might want to have a look at the PAiA Theremax, a relatively cheap kit theremin that has CV (control voltage) outputs for pitch, volume, velocity, and gate/trigger.  These should be easy to add to a MIDIbox through an AIN module.

 

http://www.paia.com/theremax.htm)

I have made the Paia theremin and it works well with the mbhp analog voltage inputs.

With the theremax you get four cv outputs, one of them is a gate on off, which is controlled with how fast your movement is towards or from the volume antenna.

The Theremax probably need to be tuned almost every time you use it because it is quite sensitive to what is around it. the antennas pick up electricity from cables or metal.   Tuning is done by turning two pots on the circuitboard (one for the picth antenna, one for the volume antenna), i think I would be a good idea to put these pots on the outside of the theremax together with the two finetuning pots that is already there.

The output voltage from my theremax isnt spot on 0-5 volts. When i have tuned the theremax I can get midi values in mbhp from approx

5-120.

I use the theremax and mbhp together with reaktor.

Another link to an optical theremin is:

http://www.stoffelshome.de/abeam.html       and  

http://www.stoffelshome.de/m_ir_dyn.html

Regards Pelle

[Guest Ryan]

Hi pelle!

5-120 is good enough! but... i dnt wanna buy any kit:) i'm looking at other theremin plans thou... but i cant test it until i complete my box, so i'll have to wait.

Regards!

Ryan

[Guest Ryan]

too bad... the links you gave looks good but they're in german:(

[Guest blafferen]

Hi Ryan,

In reply to your inicial post, I also stumbled on robobix scematic,  when searching the internet for Infrared distance measurement

 

I contakted him as he live in denmark as i do. He told me it is an old scematic and he didnt suggest using it as it is, but he would help me and a friend in developing an ir motion sensor.

The project stranded half a year ago because of lack of time, and because me and my friend is not experienced in electronics, but also because I found other sensors that was more approbiate for me to work with. A videocamera connected to a software called Eyesweb.

This is a very interesting combination for making interactive art, music and video manipulation. I know its not what you are looking for, but anyway..

 

regards Pelle

[moebius]

i dnt wanna buy any kit:) i'm looking at other theremin plans thou...

Well. you DON'T have to buy a kit or even PCB.. ;) PAIA has a very good attitude towards DIY. So, schematic is there on their website with notes about design. It might prove useful.

Bye, Moebius