Power supply connection question for tube circuit?

[solderman]

Hi All
OK, this might be a bit of topic sins it's an Amp question and not about effects. I was searching for a circuit for a tube based reverb designed for subminis when I stumbled on those two small tube amps, one for subminis like the Zevex nano head and the other for normal small tubes. After have successfully built the frequencycentral vibracaster with 12AU7 it occurred to me that I might get away with placing to tubes of that size and a small output transformed and filter caps on a Hammond sized box like the Nano head.
So I want to merry this circuit
http://amps.zugster.net/file_download/7
With this hi voltage power supply
http://www.ledsales.com.au/kits/nixie_supply.pdf
Or maybe this power supply used for a Nanohed type submini amp.
http://jjs.at/electronic/class_a_subminiature.html
My question is:
In the (http://amps.zugster.net/file_download/7) circuit I don't understand the connection from the PS transformers fillment secondary to the pin 2 of the 6AQ5 tube? To me it looks like it's inducing AC at half the voltage(R1 and R2 like voltage dividers)  of the PT:s fillment secondary to the Catode of the tube?? Have I read the schematichs wrong or what am I missing here. The reason for the question is that I wane use a 12V DC type of PS to keep it small enough to fit in a Hammond 1950B.
Thx
//Solderman

[drewl]

Well it's a common trick to float the filament ground reference to reduce hum, why they chose the output tube cathode as a DC reference I don't know.
You could just ground the the two 100ohm resistors without connecting them to the cathode.

[solderman]

Thx
Wont be a problem to me though I'm gonna use DC for the filament and that wont cause any hum.

//Solderman

[frequencycentral]

With this hi voltage power supply
http://www.ledsales.com.au/kits/nixie_supply.pdf
Or maybe this power supply used for a Nanohed type submini amp.
http://jjs.at/electronic/class_a_subminiature.html

I would go for the first of those two PS, as the BC547 regulates it more safely than the zeners in the JJS design. It should be possible to tweak the voltage divider so the BC547 turns off the 555 at a higher voltage than the spec, thus giving a higher B+.

[solderman]

With this hi voltage power supply
http://www.ledsales.com.au/kits/nixie_supply.pdf
Or maybe this power supply used for a Nanohed type submini amp.
http://jjs.at/electronic/class_a_subminiature.html

I would go for the first of those two PS, as the BC547 regulates it more safely than the zeners in the JJS design. It should be possible to tweak the voltage divider so the BC547 turns off the 555 at a higher voltage than the spec, thus giving a higher B+.

Thx, Yes that's also what I plan to do. I will change the C4 to 22uF/250V and add a R=~1K/3W and a C 22uF/250V to feed the OT with and use the same B+ for the 12Ax7 and the pentode switch might have to lower R16. I think I just have to bread board it to start with and test as usual. As my day job at the moment takes all my time it wont happen to mid Mars. 

//Solderman

[frequencycentral]

Cool Anders - I'm excited to see what you come up with. I'm planning to breadboard that nixie PS myself when I get the parts (I'm missing inductor, mosfet, diode) as I plan to build a push pull amp using two 7327 dual triodes (mil spec 6021) and a Hammond 125A. Good luck - shame we have to wait until March to see your results though!

[Ice-9]

I've just had a look at the 2 circuits and i like the nixie one, using the 555 as an astable looks like a good way to get high voltages from a low component count. I will have to try this SMPS out. I have just looked at rapid electronics website for the inductor and it looks like a readily available component and at £0.75