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 Forum index » DIY Hardware and Software
Lasertron: Light controlled, laser sound machine.
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JingleJoe



Joined: Nov 10, 2011
Posts: 878
Location: Lancashire, England
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PostPosted: Thu Mar 08, 2012 2:27 pm    Post subject: Lasertron: Light controlled, laser sound machine.
Subject description: PEW PEW PEW LAZORS!
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The basics:
-Two oscillators
-Light controlled
-Two settings; LFO control and straight light control.
-LFO has rise and fall time control
-Pulse width control.
Laser sounds ensue.

More details:

This device is made of junk, recycled parts and wood and metal from sweet tins Laughing
Two LDR's (light dependant resistors) are used to make two voltage dividers which provide control voltages which are fed into two simple VCO's. The LDR's can be switched between +V and the LFO. The LFO is the charge and discharge of a cap in a standard CMOS schmitt oscillator, thus the peak to peak of the wave is only about 1V and it is biased up a bit. An op amp is used to remove this bias and amplify the wave to 0V to +V peak to peak voltage.
The charge and discharge periods of the LFO can be changed independantly, this allows you to make a saw or ramp shaped LFO waves for great laser sounds as well as a triangle LFO for siren sounds and anything inbetween!

I almost forgot: The 100k resistors in the mixing stage can be anything near 100k, I used 180k and 120k because I had no 100ks left.

I will post some sounds soon.

P.S. I also forgot to say, that if you use a different power supply voltage you will need to tweak the resistor values of the pulse width resistors/potentiometer and the non-inverting op amp stage.


lasertron.jpg
 Description:
Circuit diagram, enjoy my childish handwriting :D
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This image has been reduced to fit the page. Click on it to enlarge.

lasertron.jpg



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Green Dungeon Alchemist Laboratories

Last edited by JingleJoe on Sat Mar 10, 2012 12:46 am; edited 3 times in total
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JingleJoe



Joined: Nov 10, 2011
Posts: 878
Location: Lancashire, England
Audio files: 14

PostPosted: Thu Mar 08, 2012 3:15 pm    Post subject: Reply with quote  Mark this post and the followings unread

Lasertron!

With P.E.W.P.E.W.P.E.W. Technology: Photo Electric Wave Producer Encorporating Working Pulse Energization Width.


lasertron.mp3
 Description:
about half way through I turn the LFO all the way up to 11 and things get really interesting :)

Download
 Filename:  lasertron.mp3
 Filesize:  7.44 MB
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PHOBoS



Joined: Jan 14, 2010
Posts: 1889
Location: Moon Base
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PostPosted: Fri Mar 09, 2012 4:25 am    Post subject: Reply with quote  Mark this post and the followings unread

nice, thanks for sharing

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dougseidel



Joined: Feb 10, 2010
Posts: 63
Location: NJ

PostPosted: Fri Mar 09, 2012 7:27 am    Post subject: Reply with quote  Mark this post and the followings unread

You are making a lot of nice instruments - i't fun to see what you're up to. Also, this drawing is very nice!
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JingleJoe



Joined: Nov 10, 2011
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Location: Lancashire, England
Audio files: 14

PostPosted: Fri Mar 09, 2012 8:18 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks chaps Smile I cannot begin to explain how much fun this thing is to play! I'd really like to make another one and add a filter and envelope with a "trigger" button, maybe multiple LFO's too.
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mrmrshoes



Joined: Feb 19, 2011
Posts: 73
Location: Newcastle Upon Tyne
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PostPosted: Fri Mar 09, 2012 4:36 pm    Post subject: Reply with quote  Mark this post and the followings unread

nicely done man.

i like it.

I'm trying to get my head around the LFO non inverting op amp section.
I know you've got a scope. (i've seen a couple of your vids) It must help seeing the wave forms for finalizing values and what not.
Great idea by the way.

Also on a off note, where did you obtain a 4089 chip. (I'm in the uk too) I can't find one anywhere. Really want to try that chip out.

keep up the good work man

cheers
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JingleJoe



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PostPosted: Sat Mar 10, 2012 12:35 am    Post subject: Reply with quote  Mark this post and the followings unread

mrmrshoes wrote:

Also on a off note, where did you obtain a 4089 chip. (I'm in the uk too) I can't find one anywhere. Really want to try that chip out.

An old electronics shop called Progressive Radio Electronics; these 4089's could be over 15 years old!
I suggest you look for any privately owned electronics shops which have been going scince the 70's Laughing There are acctually two in my area, but I had to do a reasonable amount of googling to find them both. Get searching! Wink

Now regarding the op amp stage, you mean the one after the LFO? That one is to remove the DC offset of the charge/discharge wave of the capacitor and amplify it to the maximum the op amp can, without chopping the top off!

In order to find the offset of the wave I think I used a voltage crossing detector (a simple op amp comparator like the two used for PWM in this circuit) adjusting the crossing voltage with a pot untill the wave at the output of the crossing detector was a tiny thin pulse (scope used for that) then checking the voltage at the pot with a voltmeter tells you the offset Very Happy
I did it that way because my scope is a bit crap, the different ranges are not calibrated properly and can be off by 2 volts sometimes, so it's only really good for seeing waveshapes.

mrmrshoes wrote:

keep up the good work man

Thankyou Smile I will!



This device goes on exhibition temporarily at the Liverpool World Museum today Very Happy

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TheAncientOne



Joined: Dec 26, 2006
Posts: 146
Location: United Kingdom

PostPosted: Tue Mar 13, 2012 7:03 am    Post subject: Reply with quote  Mark this post and the followings unread

Old times! I used to shop at PRS when I was a student in the 70's. I remember buying lots of exotic Plessey Telecoms scrap, including 'Trimphone' ringer PCB's and strange discrete - transistor auto diallers.

Like fool I left a superb 5V +/-15V supply I bought from them behind when I moved house. Just before seriously getting back into synth building.

Did you also go to Bert Ault's at Birkenhead? Now he did have some radical scrap. I bought a computer front panel covered in neon indicators, and still have a few other bits. I never could afford one of the inertial platform I saw there.

The 'Computer Junk Shop' at Widnes is still going: http://www.mechanelec.co.uk/computerjunkshop/

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JingleJoe



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PostPosted: Tue Mar 13, 2012 7:55 am    Post subject: Reply with quote  Mark this post and the followings unread

Fantastic Very Happy
I have never been to Bert Ault's I will look him up Smile

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TheAncientOne



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PostPosted: Tue Mar 13, 2012 8:43 am    Post subject: Reply with quote  Mark this post and the followings unread

Sorry, my bad, I think Bert retired a long time ago.

I remember lugging home a huge linear 5Volt supply for my Sort of Polysynth/expanded organ, that was largely built from TTL logic. It must have weighed about 20lbs. I think it cost a whole £4 in those days a small fortune to a young would be student. Walked and took the bus. as I recall. I think Bert knocked the price down then I would have the fare home.

Don't seem to have many places like that these days, though I think Anchor Surplus are still trading.

I love the Lazer sound machine, by the way. I might dig out some perfboard over the weekend. Thanks

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JingleJoe



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PostPosted: Tue Mar 13, 2012 11:55 am    Post subject: Reply with quote  Mark this post and the followings unread

Where about is Anchor surplus then? I want to visit all the remaining electronics shops!

Thanks for the compliments on my device Very Happy
One could make a VC-LFO to control the VCO, using the VCO circuit but with a big cap, controlled by the LFO already provided it would make for some very interesting sounds Smile
All I wish I had done with this device is add an arrangement like this for switching the LFO cap:

Code:


          |
          |
          o
         /
      o      o
      |      |
     ===    ===
      |      |
       ------|
             |
            ___
             -
             '

The caps would be two very different values for two different ranges.
Even without this I am totally happy with this device Smile I can even play tunes on it; with alot of practice and precision hand movements.

I'll get some photos soon because I plan to sell this contraption.

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