6V6 Series Heater Wiring

[plexi50]

I have another power transformer with a 12V heater voltage. How do i wire the 6V6 tubes in series? From there i think i got the preamp tube wiring right where pin 4 & 5 will each have a lead from the 6V6 heater wiring

[jeff]

Does the 12V heater have a grounded center tap? If so each side is 6V to ground.
I pretty sure you can ground pin 7 of each 6V6 and use one heater wire to pin 2 of one 6v6 and the other to pin 2 of the other 6V6.

I pretty sure you can do that even if it doesn't have a center tap. You'd be using the tubes to create an artificial center tap instead of having to use two 100 ohm resistors.

Can anyone comfirm this or put more elequently what I'm tring to say?

BAD IDEA

[TIMBO]

Hi plexi, I used 12v heaters for this one works great.

[jeff]

TIMBO are you using the 47ohm restsiors to create an artificial CT and lifting it using the voltage divider? I think you can omit the 47ohm resistors and use the tube's filiments as a CT(the connection between 4 of one tube and 5 of the other). If there's 12V AC across two 6V tubes in series, from the point of refrence of the series connection of the two tubes, one swings +6V when the other swings -6V and vice verca.

BAD IDEA

[plexi50]

No CT. Using 2 100 ohm 2 watt resistors to ground as artificial CT. Not sure how to wire the 6V6 heaters

[HotBluePlates]

Same as what Timbo shows:

Connect pin 7 of one 6V6 to pin 2 of the other. Now, there remains an unused pin 2 and pin 7 of these 6V6's. Connect your 12.6v winding across this series string.

If you don't have a center-tap, then connect a series string of 100Ω resistors across the heater winding as an artificial center-tap, as you would with any amp.

[plexi50]

I was replying to HBP and forgot the Quote: reply, the phase of the output voltage is retarded."

So am i with series wiring. I still dont quiet get it.

Is this connection of a wire going from pin 7 of one 6V6 to pin 2 of the other 6V6 at this point completed?

Are heater leads connected as follows:
One to pin7 & one to pin2 of the remaining pins of the 6V6 tubes with 100 ohm to ground at those points?

[TIMBO]

Sorry Jeff, I'm not sure of your question,the only thing i can say is that i tend to fine stuff and try to adapt it to my use and if it is how i have drawn it that is how it is, WHY it is like that, hopefully Daryl will chime in as i pinched it from one of his builds and its worked for me.

[darryl]

...hopefully Daryl will chime in as i pinched it from one of his builds...

Who rattled my cage ???   



Circuit 1 above is the arrangement HotBluePlates described earlier in this thread.

Circuit 2 is what jeff described.

Either method will work, although I prefer to use circuit 1. With circuit 2, an output valve flashover from pin 3 to pin 2 might allow the full plate voltage to pass through all the valve heaters on its way to earth. 

This amplifier uses a separate 12 volt heater transformer, and has 6V6's with their heaters in series, as per circuit 1.

[jeff]

OK. Thanks for explaining why that's a bad idea.

[plexi50]

Ok that diagram matches with what i thought you all were saying. I wired the 6V6 up last night at 2:00 am. It's morning and i just finshed wiring all the preamp tubes/pin4 & pin5.  Amp is nice and quiet. Thanks a million all you fellow amp maniacs!

[sluckey]

In my best Foghorn Leghorn voice, "I say boy, write it down this time."   

[plexi50]

In my best Foghorn Leghorn voice, "I say boy, write it down this time."  

I say,I sa,I say son put dem diagrams in a folder. Yeah i have been thinking about the EL84 series wiring post of a few months past. I am getting forgetful a lot latley. Amphimers. 

[Willabe]

Amphimers.         

[plexi50]

I have a better idea! Im just going to print out the diagram and glue it in front of me so i can never forget how series wiring is done

[darryl]

I have a better idea! Im just going to print out the diagram and glue it in front of me so i can never forget how series wiring is done

An even better idea!  Tattoo this image on your forehead, and you'll be reminded every time you look in a mirror.   



 

[PRR]

> an output valve flashover from pin 3 to pin 2 might allow the full plate voltage to pass through all the valve heaters on its way to earth.

IMHO, probably harmless. Heater impedances are much lower, normal current much higher, than plate currents. The high-volt winding will probably melt before the 6V6 heater pops. 

IAC, if you have shorts across power-tube pins, "something" is probably gonna blow, and the possible combinations are too many to predict/prevent. Wire cleanly, use good tubes, and keep your soldering iron handy just-in-case.

[plexi50]

Rarely get a hold of transformers with 12V heater voltages. Tattooed 11"x8" printout now on wall

[DummyLoad]

love the avatar plexi...

--DL

[plexi50]

love the avatar plexi...

--DL

Thanks DummyLoad. It's all Steves fault. I say,I sa,I say Steves fault 

[sluckey]

Tattooed 11"x8" printout now on wall

We want proof! Where's the pic?

[billcreller]

Some time ago, I used 12V6s & other octal 12 volt tubes to do one.  Had a bunch of the 12V6s but had to buy the 12 volt octal pre-amp & PI tubes, the 12SJ7, & the 12SL7.  It worked OK.  Just another Valco type I gave away.
 Don't remember where I got the PT with that heater voltage.....

[plexi50]

I get old gear around town and strip some of it out for parts.  Every now and then a 12V heater will pop up. Unexpected of course until after i test the transformers. If they have a 5 volt tap for a recto then i have to use them.
I have been saved by a diagram and Fog Horn Leg Horn!
Heres the proof!