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Snaper
Joined: Feb 28, 2014 Posts: 217 Location: Hungary
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Posted: Fri Jan 02, 2015 3:21 am Post subject:
Re: "Crushed Glass" - Dual TUBE Oscillators |
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frequencycentral wrote: | I put this noisy little MF together a couple of weeks ago on the breadboard. It seems to be getting a bit of interest elsewhere so I thought I'd start a thread for it. It uses the application of low-frequency feedback oscillation (motorboating) to create two pulse oscillators with roughly a 25% duty cycle. The top osc is LF, the bottom one HF. Not a perfect device by any means, but fun and capable of making an unholy racket. I used two 6111 submini tubes, but it should work fine with 12AU7, possible 12AT7 and 12AX7 too - just change the pinouts and power the heaters correctly. I breadboarded it, recorded it, drew up the schemo then took it apart. I made it up again from the schemo a week later just to check it wasn't a fluke! I expect it would benefit from a buffer at the output. The pots don't work across the entire range. It would be cool to use a joystick instead of pots, and possibly feed the two osc into a ring mod. Fully open for hacking, development and general ear abuse. Oh, and if you do build it you're as crazy as me!
Soundclip: http://www.aronnelson.com/DIYFiles/up/Crushed_Glass_Sample.mp3
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Regarding the schemo what I've found in Kens site, is it possible to add a CV in to pin 2, before the 1M resistor?
http://www.cgs.synth.net/tube/vco.html |
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LFLab
Joined: Dec 17, 2009 Posts: 497 Location: Rosmalen, Netherlands
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Posted: Fri Jan 02, 2015 6:15 am Post subject:
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Read this thread, I've asked for voltage control earlier, not easy it seems. |
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micyclebicycle
Joined: Jun 06, 2013 Posts: 8 Location: USA
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Posted: Wed Nov 04, 2015 8:26 pm Post subject:
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hey Im going to try this out with a set of 12ax7
Does this look right for the pins>?
(removed old schematic) Last edited by micyclebicycle on Tue Nov 10, 2015 1:05 pm; edited 1 time in total |
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LFLab
Joined: Dec 17, 2009 Posts: 497 Location: Rosmalen, Netherlands
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Posted: Fri Nov 06, 2015 3:16 am Post subject:
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Connection to the plate-grid-cathodes are ok, but heater is off.
Connect 12v between pin 4 and 5, leave pin 9 open. If you connect the heater supply according to your drawing, you'll short it. |
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micyclebicycle
Joined: Jun 06, 2013 Posts: 8 Location: USA
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Posted: Fri Nov 06, 2015 11:18 am Post subject:
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There are 2 tubes, two heaters in series?
Am i missing something? |
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gdavis
Joined: Feb 27, 2013 Posts: 359 Location: San Diego
Audio files: 1
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Posted: Fri Nov 06, 2015 1:40 pm Post subject:
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The problem as I see it is that the 12ax7 needs twice the heater voltage of the 6111. Connect the two tubes in parallel instead of series so they both get 12V (pin 4 of both tubes to 12V and pin 5 of both tubes to ground). _________________ My synth build blog: http://gndsynth.blogspot.com/ |
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LFLab
Joined: Dec 17, 2009 Posts: 497 Location: Rosmalen, Netherlands
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Posted: Sat Nov 07, 2015 12:53 am Post subject:
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I am sorry, yes there are two tubes, each of the tubes need 12v across their heaters.
12ax7 can use either 6or 12v heaters by using the centre tap (or not). |
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micyclebicycle
Joined: Jun 06, 2013 Posts: 8 Location: USA
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LFLab
Joined: Dec 17, 2009 Posts: 497 Location: Rosmalen, Netherlands
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Posted: Wed Nov 11, 2015 6:57 am Post subject:
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Looks good |
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Krupa
Joined: Mar 20, 2021 Posts: 13 Location: UK
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Posted: Sat Mar 20, 2021 2:44 am Post subject:
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I’m going to try putting this one together soon but I’ll probably have to order the tubes from Ukraine or maybe the USA, looking forward to it though!
I’ve got access to a bunch of other tubes and want to try using them in an art installation so I’m hunting for other oscillator designs that run at low voltages using these, lots of old UK model radio and TV valves that are pentode and some triode - is this crushed glass design unique in its low voltage nature or are there many other ways of doing this? |
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Krupa
Joined: Mar 20, 2021 Posts: 13 Location: UK
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Posted: Wed Mar 31, 2021 3:35 pm Post subject:
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I’ve been using what skills I do have to put one of these together the last few days and finally got proper oscillation today after swapping out the pots for fixed resistors as either I’m out of my depth or there’s something not right with the one I have. This eliminated the massive ground hum I’d been getting and kickstarted the motorboating in great style. Lots of swapping resistors and capacitors while sampling furiously through an irig into my iPad and I’ve just jammed this out in AUM using one sample as a drone, another as a granular instrument accompanying simple piano and a geoshred oboe noodle...
https://soundcloud.app.goo.gl/eQ1GCKCoD7Jdg5cF6
Dead pleased with myself, just need more components and a few more boards 😁 |
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vladosh
Joined: Aug 02, 2010 Posts: 659 Location: macedonia
Audio files: 46
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Posted: Mon Apr 05, 2021 10:31 am Post subject:
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wondering if this can work with a vactrol like in LPG ,to get these to have voltage control ,should work ,it's a dual vactrol , the NLC schematic for LPG works great with LCR vactrols ,so it can be cheap as well _________________ http://synthacks.blogspot.com/ шематикс |
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Krupa
Joined: Mar 20, 2021 Posts: 13 Location: UK
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Posted: Mon Apr 05, 2021 9:34 pm Post subject:
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Vactrols will be one of my next experiments now that I’ve had some success with this one - do you have the schematic for the one you mention @vladosh? If so is there any chance you could link to it? I’ve had limited success with a photoresistor instead of a potentiometer but I think the one that I have is of limited range...
If anyone has any other insights or good experiments with this design or similar I’d love to see them as I’m putting together ideas to workshop these in the community... another thing I did try with some success is adding a small capacitor after the potentiometer which seemed to change the timbre somewhat. In my muddied thinking it should smooth off the attack of the pulse’s rise, but I’m likely well wrong on that... |
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vladosh
Joined: Aug 02, 2010 Posts: 659 Location: macedonia
Audio files: 46
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Krupa
Joined: Mar 20, 2021 Posts: 13 Location: UK
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vladosh
Joined: Aug 02, 2010 Posts: 659 Location: macedonia
Audio files: 46
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Posted: Tue Apr 06, 2021 12:30 am Post subject:
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that is a 7 way - vactrol ,i have some ldr's leftovers so i thought i'd give it a try ,you can check the spasm schematic at nlc sitte so to understand it ,it's just one led and 7 x photoresistors around it _________________ http://synthacks.blogspot.com/ шематикс |
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Krupa
Joined: Mar 20, 2021 Posts: 13 Location: UK
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Posted: Tue Apr 06, 2021 12:32 am Post subject:
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Oh wow, that sounds tripping, I’ll give it a look, thanks! |
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Krupa
Joined: Mar 20, 2021 Posts: 13 Location: UK
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Krupa
Joined: Mar 20, 2021 Posts: 13 Location: UK
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