New Effect: "Bipolar Disorder"

[frequencycentral]

'Bipolar Disorder' – another badly engineered circuit from the King of the slightly below average.







frequencycentral, in association with Doctor Analogue proudly presents 'Bipolar Disorder', a tube based tremolo with switchable dual speeds and the ability to ramp between the two – a la Leslie.







The circuit provides a nice soft tube crunch when hit hard by P90s or Humbuckers. I don't have a single coil guitar to try it with. To achieve a nice clean tremolo play gently, or use the guitar volume knob.

The circuit was designed for a 9 volt supply. The audio section is entirely tube, using a single 12au7. The LFO is a LM13700 dual transconductance opamp. A dual opamp, a few caps and a handful of resistors completes the package.

If you haven't used a 13700 before, they are far simpler than they look on a schematic. Please note the orange box around the chip, everything in the box is 'on chip'. Here's a more pictoral view:







The dual opamp used was a TL082, equivalents should work just fine. The first opamp is a buffer for the 470K/4.7uf slew limiter before it hits the 13700 CV input. The second opamp is a buffer for the 13700 triangle output before it hits the tube.

I 'hardwired' the slew rate, as I found the 'sweet spot' and wanted to nail it down. You may want to add 'Slew' pot – play about with the 470K/4.7uf slew limiter values. I hooked up the 'Speed' stomp switch with a couple of red LEDs to get a visual on which speed control is selected, one either side of the green rate LED.

Please feel free to suggest any modifications or improvements!!

Thanks to everyone who helped and guided me with this project: gez, Paul Perry (Frostwave) and nelson. Special thanks to The Tone God, whose 'Bullitt' provided the inspiration and a starting point.

Rick

[Berger]

this looks fantastic!

[frequencycentral]

this looks fantastic!

The legs or the schematic??? 

[Berger]

The schem, glad to finally see it. I was thinking of making a tube trem sometime as well. do you have any trem schematics that I could use for reference?

-Aaron

[frequencycentral]

The Tone God's 'Bullitt' was my start point: http://www.geocities.com/thetonegod/bullitt/bullitt.html

[Berger]

fantastic! not sure how I'm missed that. Thanks.
Edit: just read through the link there is a lot of great info there.
i may have to breadboard some things tonight

[frequencycentral]

fantastic! not sure how I'm missed that. Thanks.
Edit: just read through the link there is a lot of great info there.
i may have to breadboard some things tonight

My pleasure! I breadboarded this using a 6111 submini tube as it's leg slot right into the board. Just used a LM317 and a 1k trimpot to get 6.3v. The completed 12au7 version works exactly the same.

[Pushtone]

Thanks for sharing Rick, this looks like a lot of fun.
I built the Bullitt and was thinking about a version sans tone stack.
The dual ramping speed control is such a nice touch that I might give this a try with my signature tubes-on-top look.
If I do I'll post a layout.

Dave

[Renegadrian]

Rick, it seems a great project!!! Hopefully I'll start breadboarding something with a couple of tubes some day...
Great work, my friend!!! 
Now let us listen to it!!! 

[Jimmy-H]

Hi Rick!

Nice job!!
I really love the legs........uuuuh pedal I mean.
When I have the time, I will build one.
Does it work with the 6111 tube just as good as the 12au7?
Because  have a couple lying around.
Or do you prefere the 12AU7.

Keep up doin' the good work Rick 

And uuh God Save The Queen!!!
(I don't know why I said that, probally because you are an English chap!)

[frequencycentral]

Does it work with the 6111 tube just as good as the 12au7?
Because  have a couple lying around.
Or do you prefere the 12AU7.

It appears to work just as well with either. I decided on 12au7 in the final build because I needed a big enclosure anyway for the 4 pots - it could be 6 if you added input attenuation and a 'Ramp Time' pot.

Using 9 volts and a LM317/1K trimtop to get 6.3 volts for the 6111 heater, I noticed that the 317/6111 don't get anywhere near as hot as on my 12 volt Subcaster. Even after hours on the breadboard they were cool enough to touch. I didn't try the BD at 12 volts, as I'm all geared up for 9 volts on my pedalboard.

I still have 4 unused 6111s in my parts bin too - I have an idea for a tube bit crusher though, so I may use one for that project, as it will only have 2 pots, and so will need only a small enclosure.

Now let us listen to it!!! 

Yeah, I must do some soundclips!!

[frequencycentral]

I'm made a couple of small changes to the schematic. For some reason I had put the 1M pulldown resistor before the 1uf cap at the input, now it's in the right place, and I've also added a 100k to ground at the input - this could be a smaller value if you want the effect to be cleaner with guitar at maximum volume. Also, the pulldown resistor at Pin 2 of the second triode was showing as 1M, this was an oversight, and should read 100K - the combination of the 0.01 and this resistor also form a highpass filter to limit LFO bleed into the audio path. I've deleted the original schematic from Photobucket and substituted the new one with the changes - so the schematic at the top of this page is now correct.