Inspired by the Valve Caster

[petemoore]

http://ourworld.compuserve.com/homepages/Bill_Bowden/page12.htm
  This page helped me out a lot ! ! !
  The pinout text is so much clearer than the double-backward junk RS barely even prints on their box.
  I just went through part of this yesterday...
 
  http://www.national.com/mpf/LM/LM317.html
  Says guaranteed 1.5 amp of current output, wow, that would take some heat sinking and get warm.
  So you calculate your heater current draw and...compare and make it < the power regulator rating, a second chip could share the load somehow.
  The heat may begin its 'silent talking' about thermal conditions, but if you haven't touched it for 1 second or so, touch it very fast, because these things can leave marks on you. If it starts gettin' hot fast in <10 seconds or so you should be able to tell something about how much heat sinking will save the chip, as you cut the power and fix it.
  For the 12au7 that was a 1'' square of coppersheet-heatsink, selftapping screw...plenty, because now it just gets a little warm.
  Watch that the heatsink and chip body stays isolated from Gnd. or other connections.
 

[DougH]

Looks pretty cool, Jered!

[frequencycentral]

So for this particular project, there are two tubes, each with two heaters.  Could I use something like an LM317 to provide 25.2V at 300 mA and run all four heaters in series or is that not recommended?  I am just thinking that my power supply probably wouldn't do 600 mA (only rated to 500 mA).  Also, the schematic for the dual triodes I have seen look like the heaters are connected to each other internally, is this correct?  Because then I could just run the power in to one heater and then from the pin of the second heater to the second tube.  Can I do this or am I oversimplifying the problem?

No - there are two tubes, but each tube only has one heater, so you can run the two heaters in series at 12v / 300ma. Th

Here's a diagram:

[Ripthorn]

Thanks Rick, you answered my questionperfectly.  I was wondering about whether there was just one heater or two in the tube, I guess the pinout just confused me by listing two pins as heater pins.  This should be a fun project.

Jered, thanks for sharing, this is going to be a blast.  By the way, do you have a name for this project?

[petemoore]

  Two resistors form a voltage divider...makes for a warm 6v right there in the middle !

[frequencycentral]

  Two resistors form a voltage divider...makes for a warm 6v right there in the middle !

The tubes' heaters allow 300ma to pass when there is 6.3V across them, and they are resistive. That means, as you properly compute, that the resistance of a heater is 6.3V/0.3A = 21 ohms. If you have 12Vdc and want to drive 300ma into you heaters, you can do that easily enough without using a voltage divider by putting a resistor in series with the heater. The resistor is R = V/I = (12-6.3)/0.3 = 5.7/0.3 = 19 ohms. It would dissipate 5.7*0.3 = 1.7W and you'd need to use a 3W resistor to keep it from runnig at about 200C surface temp.

A 20/20 divider will not give you what you think. A divider composed of 20 ohms / 20 Ohms from 12V will gie you 6V only when there is no load on the 'Y"s. This produces 6C only when it's not loaded.

http://www.diystompboxes.com/smfforum/index.php?topic=70212.msg564334#msg564334

[Jered]

Jered, thanks for sharing, this is going to be a blast.  By the way, do you have a name for this project?

  Giving it a name never occured to me. So, go ahead a name it if you like.

[Ripthorn]

I will probably need to hear it first, but the first thing that came to my mind as soon as I saw it was something like the Uber Tuber.  What do you think? 

[Jered]

  Fire it up, then give it a name. Many times I've fired up a new circuit and quickly called it sh_t. 

[frequencycentral]

  Fire it up, then give it a name. Many times I've fired up a new circuit and quickly called it sh_t. 

Hahaha! Thats funny - but I do it the other way around, come up wth a cool name then design the circuit.

[Ripthorn]

Well, I am still waiting on parts to get here, but when I do build it, then I will see what name works and all.

[bancika]

   This will get you there and then some.

where did this design come from? looks very interesting but I haven't seen it before. Is it tested?
Is there a layout for it?

Thanks,
Bane

[Ripthorn]

Not sure where it came from, but I have built it minus the tone section and with a few substitutions.  No layout that I know of.

[bancika]

how do you like it? can you compare it with any other amp/pedal?

[Ripthorn]

I have found that the first two gain stages actually give a very clean sound (when used with 6111), very warm and fat.  All four gain stages give a great classic sounding distortion.  I think it is very versatile, but a if you want something really sparkling, either use it with something like a tonemender or go with a different design.  I didn't find it to be "ultra high gain", but then again I wasn't using 6021's, which have a little more gain than 6111's.