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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: 202
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: 461
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: 7
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: 461
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: 7
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
Audio files: 1

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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My synth build blog: http://gndsynth.blogspot.com/
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LFLab



Joined: Dec 17, 2009
Posts: 461
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: 7
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:  41 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: 461
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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