russian 6j5b-v penode instead of a 12au7?

[aran.e666]

Hi all, im new here  but have been building pedals for a year now. My subject is a tube boost/overdrive called the valve caster. This uses a 12au7 tube or anything close. The 12au7 uses 2 cathodes, 2 anodes and 2 grid pins however the mini russian 6j5b-v uses 1 cathode,  1 anode and 3 grids. Both have 2 heater pins. I know the pinout of the 12au7 and 6j5b-v but it would require 2 cathodes so one could act as the gain control? Any ideas would be massively appreciated. Also the schematic is the valve caster by IVIark (will post if I have permission from him) and I have tried to draw out my own schem with the russian pentode but Im not sure if it would work. Thanks

Aran 

[PRR]

Beer comes in 6-packs.

The 12AU7 is a "2-pack", two triodes in one.

The 6j5b-v is a "1-pack", one tube (though a fancy tube with extra bits).

If I'm thirsty for a 2-pack of beer, a 1-pack doesn't quench my thirst, even if it has extra bubbles.

While you "might" do a similar thing with one pentode as two triodes, that's a complete re-design, which I suspect you are not ready to do yet, and too big a job to do casually (ie free).

The BEST path is to get a 12AU7. They are not expensive. The power bits and the case and knobs will cost you more than the tube.

[midwayfair]

Plus, you'd need to know that the power requirements of the two tubes are the same. The 12AU7 will run on far lower supply voltage than many other tubes.

[aran.e666]

Yeah I figured, im currently working on some type of amp (will replace speaker with a jack after some resistors or something) but it is a little confusing e.g. do I need to use all the grids, what do I wire capacitors and resistors to etc. I do get that you wire caps to gnd for filters and resistors to lower the ripple in ac current but like I say I dont know if my schematic will work. Thanks

Aran

[midwayfair]

Yeah I figured, im currently working on some type of amp (will replace speaker with a jack after some resistors or something) but it is a little confusing e.g. do I need to use all the grids, what do I wire capacitors and resistors to etc. I do get that you wire caps to gnd for filters and resistors to lower the ripple in ac current but like I say I dont know if my schematic will work. Thanks

Aran

This paragraph has me very worried. Please, please be careful. You are working with mains power with enough amperage and volts to kill you. If you don't understand some basics when working with high voltage, you need to step back and be absolutely certain you understand those before you get anywhere near a soldering iron, much less a power outlet. Merlin Blencowe's site has the entire first chapter of his book free online, which discusses power supplies and safety in amps. I highly recommend reading it and not proceeding until you understand it. You can then move on to reading about the basic functions and implementations of different types of tubes. But safety first.

Bookmark it: http://www.valvewizard.co.uk/

[aran.e666]

Well im trying to run it off 9-12v by starving the cathode or some thing?

[tubegeek]

It's going to be hard to predict what results you get because you are working at a voltage much, much lower than typical. Tubes do weird stuff at voltages so low. "Normal" behavior doesn't kick in until 80 - 100V although past maybe 40 or so you'll get somewhat more predictable results than the low voltage you are trying to use.

Trial and error is the only tool you'll have at such low voltages. Don't go to a higher voltage until you understand better, you'll hurt yourself.

[aran.e666]

Yeah its worth a try as long as I dont blow up a tube or... myself. Thanks

Aran