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 Forum index » DIY Hardware and Software
"Crushed Glass" - Dual TUBE Oscillators
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Snaper



Joined: Feb 28, 2014
Posts: 217
Location: Hungary

PostPosted: Fri Jan 02, 2015 3:21 am    Post subject: Re: "Crushed Glass" - Dual TUBE Oscillators Reply with quote  Mark this post and the followings unread

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

Posted Image, might have been reduced in size. Click Image to view fullscreen.

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

PostPosted: Fri Jan 02, 2015 6:15 am    Post subject: Reply with quote  Mark this post and the followings unread

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

PostPosted: Wed Nov 04, 2015 8:26 pm    Post subject: Reply with quote  Mark this post and the followings unread

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

PostPosted: Fri Nov 06, 2015 3:16 am    Post subject: Reply with quote  Mark this post and the followings unread

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

PostPosted: Fri Nov 06, 2015 11:18 am    Post subject: Reply with quote  Mark this post and the followings unread

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
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PostPosted: Fri Nov 06, 2015 1:40 pm    Post subject: Reply with quote  Mark this post and the followings unread

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).
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LFLab



Joined: Dec 17, 2009
Posts: 497
Location: Rosmalen, Netherlands

PostPosted: Sat Nov 07, 2015 12:53 am    Post subject: Reply with quote  Mark this post and the followings unread

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

PostPosted: Tue Nov 10, 2015 1:04 pm    Post subject: Reply with quote  Mark this post and the followings unread

Updated


Crushed 12ax7.jpg
 Description:
Crushed Glass schematic, for 12ax7 tubes
 Filesize:  89.03 KB
 Viewed:  232 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

Crushed 12ax7.jpg


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LFLab



Joined: Dec 17, 2009
Posts: 497
Location: Rosmalen, Netherlands

PostPosted: Wed Nov 11, 2015 6:57 am    Post subject: Reply with quote  Mark this post and the followings unread

Looks good
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Krupa



Joined: Mar 20, 2021
Posts: 13
Location: UK

PostPosted: Sat Mar 20, 2021 2:44 am    Post subject: Reply with quote  Mark this post and the followings unread

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

PostPosted: Wed Mar 31, 2021 3:35 pm    Post subject: Reply with quote  Mark this post and the followings unread

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
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Location: macedonia
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PostPosted: Mon Apr 05, 2021 10:31 am    Post subject: Reply with quote  Mark this post and the followings unread

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
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Krupa



Joined: Mar 20, 2021
Posts: 13
Location: UK

PostPosted: Mon Apr 05, 2021 9:34 pm    Post subject: Reply with quote  Mark this post and the followings unread

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
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PostPosted: Tue Apr 06, 2021 12:02 am    Post subject: Reply with quote  Mark this post and the followings unread

i had success with LPG from Non Linear Circuits ..this one : https://static1.squarespace.com/static/5e6e99e8bd2f8a6de8454feb/t/5e77dd7de08d1b666d1546bd/1584913790581/WAMOD4+lpg.pdf ,i used LCR0202 vactrols from Ali ,built two of these already ,also a Serge VC glide works good with these vactrols ,tried to make Serge Phaser aand it worked but that needed some modification to make itt work 100% ,here is my layout for this LPG http://synthacks.blogspot.com/search?q=low+pass+gate ,there is also a envelope follower and preamp on this pcb layout also from Buchla adaptation from NLC https://static1.squarespace.com/static/5e6e99e8bd2f8a6de8454feb/t/5e7808c54919f8518becb2de/1584924870162/ENV+follower.pdf ..on this board the LCR0202 are mounted on the copper side of the pcb
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Krupa



Joined: Mar 20, 2021
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Location: UK

PostPosted: Tue Apr 06, 2021 12:16 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks! They look really interesting, as does the first one on your blog;

http://synthacks.blogspot.com/2021/04/nlc-spasm-th.html?m=1


Is the circular component to the right of the op amp some sort of tube as well?
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vladosh



Joined: Aug 02, 2010
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PostPosted: Tue Apr 06, 2021 12:30 am    Post subject: Reply with quote  Mark this post and the followings unread

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
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Krupa



Joined: Mar 20, 2021
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PostPosted: Tue Apr 06, 2021 12:32 am    Post subject: Reply with quote  Mark this post and the followings unread

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

PostPosted: Wed Apr 07, 2021 12:40 pm    Post subject: Reply with quote  Mark this post and the followings unread

https://soundcloud.com/christian-krupa-1/a-short-improvisation-on-dual

I think I’m getting the hang of these wee beasties Very Happy
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Krupa



Joined: Mar 20, 2021
Posts: 13
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PostPosted: Sat Apr 10, 2021 7:04 am    Post subject: Reply with quote  Mark this post and the followings unread

Using an iphone app (drambo) to envelope them...

https://soundcloud.com/christian-krupa-1/inherent-tension
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