update about hofner krazy fuzz and tube pwr supply question

[guitarleeman]

I forgot to mention that I actually saw a Hofner Krazy fuzz at a guitar show one time. It was root beer colored and had die cast enclosure. I flipped it over and the circuit was glued to the back panel. Al I remember was it had 3 PNP transistors. Come to think of it,it looked very similar to the Selmer buzztone circuit. Can anyone confirm this? Also I had question about low voltage pwr supply for tube circuits. Can you run 2 12AX7's off of 12or 15 VDC supply and how do you create 6.3v heater tap to power up heaters of the tube?

[petemoore]

Can you run 2 12AX7's off of 12or 15 VDC supply
  Yes, it's called 'Starved Plate", check out Shaka Tube, GGG...
   and how do you create 6.3v heater tap to power up heaters of the tube?
  Check out the above links.
  ..or you could use a voltage regulator to do that.
  an LM317 should be able to do it, see data sheet, there are other VR's capable of regulating 12v down to ~1/2 that, and less...

[The Tone God]

Can you run 2 12AX7's off of 12or 15 VDC supply and how do you create 6.3v heater tap to power up heaters of the tube?

There are two supplies to deal with. The voltage to the triode sections and the heater voltage so I will go through each question with that in mind.

Can you use 12 or15v for the triode voltage ? Yes.

Can you use 12 or 15v for the heater voltage ? 12v yes. 15v no.

Can the 12v you have access to feed the heaters ? Depends on the amperage you 12v supply can offer. At 12v you need 150mA per tube to heat it so you need 300mA for two tubes.

How do you create the 6.3v for the heater ? If you have 12v you could use the 12v by wiring the heaters in series. It would save alot of work from having to create the 6.3v.

Andrew