Powering a tube with 12.6 VDC

[hesamadman]

Was wanting to make a real simple tube pre amp in pedal form. Was curious about powering it though. Do I need a full 12.6vdc or would a 12VDC supply work.

And does using DC affect anything else? Could I take my simple design that I already have and just power with DC?

[eleventeen]

12 volts will work fine. It's only 5% low compared to 12.6 volts and that's well within normal slop-specs.

[HotBluePlates]

And does using DC affect anything else? Could I take my simple design that I already have and just power with DC?

What's the design?

If you're only thinking about lighting the tube with 12vdc, that will work fine. I have a high-end microphone preamp that uses 12vdc to light the tubes (because it was readily available in a regulated power supply).

[EL34]

Go to the library page and look for this project
Tube pre amp in a pedal box

http://el34world.com/schematics.htm

I sell the toroidal transformer used to power pedal based tube projects

[kagliostro]

Could I take my simple design that I already have and just power with DC?

With DC put a flea on my ear, isn't that you want to supply 12V DC as B+ ???

If so, I know that someone has done something like that with usual 12a*7 series tubes, but I think that as to obtain

good results you must use special tubes designed for car  radio use like 12U7 tubes



K

[EL34]

This is how I did it for my project
see my link a couple replies up

[kagliostro]

For a tube pedal, Doug's system (an AC 12V wall wart + a small toroidal PT in the pedal, used "back to back") is the best way to obtain a perfect voltage in a very small unit
K

p.s.: Doug, just a clarification about the use of the toroidal transformer you sell for this use



as to be used on the pedal the 9v secondary (used as primary) must be connected in parallel or in series ?
The schematic shows paralleled, but I don't know if it refers to the transformer you sell now

[EL34]

Not sure what you are asking
The diagram up above shows the wiring I used on my project
one side is in series and one side is in parallel

[kagliostro]

What I'm asking is if the toroidal transformer you sell now is to be used with the secondaries (that here are used as primaries) in series or in parallel


I'm asking because I don't know if the transformer you sell now is the same transformer you used at the time you draw the schematic


K

[EL34]

It's the same transformer I have always sold and used in my projects, so you can use the diagram above as a reference

There are twin windings on each side
Notice that I am inputting 12 volts AC into what is normally the secondary
So it is being used as a step up tranny

That tranny can be found on this page for those that are interested
http://hoffmanamps.com/MyStore/catalog/parts1.htm

[kagliostro]

Thanks Doug, courteous as always 


Franco

[EL34]

And also notice that bridge one is making 12+ volts DC for the tube heaters
I don't remember what the actual voltage is before it gets to the regulator
The voltage regulator keeps it at 12vdc

You would use pins 4 and 5 for 12 volt heaters