Switching the dual voltage PT taps

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VelvetGeorge
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Switching the dual voltage PT taps

Post by VelvetGeorge » Wed Oct 25, 2006 8:11 pm

Let's get all the info in a thread for this. I'm getting a lot of emails.

The theory behind this is:

You switch the full high voltage supply lower taps in the secondary wind.
About 40 volts less AC supply to each side of the diode bridge results in about 100 volts less DC.

So (4) wires from the high voltage secondary are switched going into the rectifiers.

When the voltage is dropped, we also need to lower the bias voltage to maintain our intended idle current.
In the diagram I accomplish this by switching an extra resistor into the bias voltage supply from the PT.

The value of this resistor should be adjusted to make your tubes bias at the preferred current in the low voltage setting.


VG
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Post by 5150loveeddie » Wed Oct 25, 2006 8:19 pm

Cool info VG, thanks
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Post by 5150loveeddie » Wed Oct 25, 2006 8:19 pm

Cool info VG, thanks
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Post by VelvetGeorge » Wed Oct 25, 2006 8:23 pm

Nice avatar!! Thank you JF!

VG
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Post by rockstah » Wed Oct 25, 2006 8:31 pm

excellent! seems simple enough. thanks George!

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Post by Billy Batz » Wed Oct 25, 2006 10:10 pm

The allusive VV switch has finally been made public by the man himself.

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Post by 5150loveeddie » Wed Oct 25, 2006 10:30 pm

VelvetGeorge wrote:Nice avatar!! Thank you JF!

VG
Let me know if this is a little to sexy!! I'll change it!!!!
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Post by Guitar Adjuster » Wed Oct 25, 2006 11:05 pm

I think your Boobs look great, leave them alone! :twisted:

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Post by Flames1950 » Wed Oct 25, 2006 11:21 pm

5150loveeddie wrote:
VelvetGeorge wrote:Nice avatar!! Thank you JF!

VG
Let me know if this is a little to sexy!! I'll change it!!!!
She's sure got her party hats out...... :shock:
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Post by antosimoni » Thu Oct 26, 2006 5:46 am

George,
sorry but to me its not clear where I've to put that 27K res in my 1959HW, any help will be appreciated, thanks a lot to every1 :D

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Post by Flames1950 » Thu Oct 26, 2006 7:10 am

antosimoni wrote:George,
sorry but to me its not clear where I've to put that 27K res in my 1959HW, any help will be appreciated, thanks a lot to every1 :D
The 27K should already be on the turret board in the 1959HW.........that's part of the bias section which was already there.
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Post by antosimoni » Thu Oct 26, 2006 8:40 am

Flames1950 wrote:
antosimoni wrote:George,
sorry but to me its not clear where I've to put that 27K res in my 1959HW, any help will be appreciated, thanks a lot to every1 :D
The 27K should already be on the turret board in the 1959HW.........that's part of the bias section which was already there.
hi this is mine, could you please point me where this 27K res have to be placed??? lots of thanks if you can help me...
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thanks a lot for any advice will come in :wink:

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Post by wdelaney72 » Thu Oct 26, 2006 9:44 am

But George, according to the Caswell, Bray, and Assclown business model, you are supposed to keep this a big secret. :roll:

Thanks for sharing. I'm about 75% done with my 12xxx, which includes the switchable PT.

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Post by robert » Thu Oct 26, 2006 9:51 am

Hi wdelaney72,

regarding the Assclown-builders: obviously George doesn't like goop as much as Howie did in his 7umble amps...

Regards

Robert

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Post by wdelaney72 » Thu Oct 26, 2006 11:51 am

I'm sure George can find a good deal on some black epoxy.

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