Charge pump for tube projects

[TheBathroom]

So I'm the kind of person who reads a lot about stuff online before I do it. I'm trying to make a charge pump on vero that can power up to 4 ECC82's (12AU7), and I've read that the MAX1044's tend to get burnt out by red-lining the voltage input at 9v.

So I think I should go with a ICL7660 instead, for tolerance reasons, but I still don't know how much current it can supply for 4 tubes. From what I've read, 7660's can supply up to 100mA of current, and each plate can use about 25mA of current. Now I haven't experimented with this yet, but I'm just trying to take 9v up 24v, because I can't find a good voltage doubler to take 12v to 24v. I don't know how much current the plates draw at 24v, so I'm thinking of using a 24v regulator from a higher voltage source, like the 33v rail below. And for the heaters, I'll use a 6v regulator off the 9v supply.

Better yet: Is it safe to power all four tubes with the 25v rail, or could I put an inductor off the 25v rail to improve the current rating of the charge pump?

[PRR]

Welcome!

> each plate can use about 25mA of current.

Read the data:
http://www.mif.pg.gda.pl/homepages/frank/vs.html

12AX7 @ 24V can suck 0.7mA max. (*)

12AU7 @ 24V can suck 2.5mA max.

That's with plate nailed solid to B+. So where do we find a signal??

We will "always" run plate to B+ via a resistor. For best output, the tube and the resistor should be in a "fair fight", each dropping around half of the total available voltage. (Because tubes conduct poorly, we may opt for a little more across the tube.)

12AX7 @ 24V as an amplifier may suck 0.35mA.

12AU7 @ 24V as an amplifier may suck 0.7mA.

And four double tubes (EIGHT stages!) is way more than you can ever want in an audio path, unless you have so many gain-sucking frills that you need a console to hold all the knobs.

Taking IMHO an over-extreme worst-case: 8 * 0.7mA is 5.6mA. All tubewerk is +/-20%, low-volt tubewerk maybe 40% (more often low than high), so maybe 8mA total at 24V.

Don't regulate. Tubes don't need it. 27V to 24V is much too slim headroom. The tubes will eat a 27V supply and be happier for it. They do want buzz-filtering, but I ass*ume your 9V is dead-clean, and the 20KHz whine of the multiplier isn't big caps.

Given a ~~24V goal and 2 or 4 bottles, I would strongly consider a solid 24V DC supply. Four 6.3V 0.3A heaters is 7.56 Watts, which from 9V is 0.84 Amps, and that's nearly all of a good pedal supply. Before you start dickering all different voltages off it. Meanwhile a 24V DC supply does it all, and you can sometimes pull one from behind a dead inkjet printer.

Tube data:



(*) Tube current rises as grid 1 voltage goes more positive. However when grid voltage exceeds cathode voltage (Ec>0), heavy grid current flows. This is gross distortion. Audio amps "never" go positive-grid. Distortion boxes touch it, but never enough to raise plate current.