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Switching the dual voltage PT taps
Posted: Wed Oct 25, 2006 8:11 pm
by VelvetGeorge
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
Posted: Wed Oct 25, 2006 8:19 pm
by 5150loveeddie
Cool info VG, thanks
Posted: Wed Oct 25, 2006 8:19 pm
by 5150loveeddie
Cool info VG, thanks
Posted: Wed Oct 25, 2006 8:23 pm
by VelvetGeorge
Nice avatar!! Thank you JF!
VG
Posted: Wed Oct 25, 2006 8:31 pm
by rockstah
excellent! seems simple enough. thanks George!
Posted: Wed Oct 25, 2006 10:10 pm
by Billy Batz
The allusive VV switch has finally been made public by the man himself.
Posted: Wed Oct 25, 2006 10:30 pm
by 5150loveeddie
VelvetGeorge wrote:Nice avatar!! Thank you JF!
VG
Let me know if this is a little to sexy!! I'll change it!!!!
Posted: Wed Oct 25, 2006 11:05 pm
by Guitar Adjuster
I think your Boobs look great, leave them alone!
Posted: Wed Oct 25, 2006 11:21 pm
by Flames1950
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......
Posted: Thu Oct 26, 2006 5:46 am
by antosimoni
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
Posted: Thu Oct 26, 2006 7:10 am
by Flames1950
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
The 27K should already be on the turret board in the 1959HW.........that's part of the bias section which was already there.
Posted: Thu Oct 26, 2006 8:40 am
by antosimoni
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
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...
thanks a lot for any advice will come in
Posted: Thu Oct 26, 2006 9:44 am
by wdelaney72
But George, according to the Caswell, Bray, and Assclown business model, you are supposed to keep this a big secret.
Thanks for sharing. I'm about 75% done with my 12xxx, which includes the switchable PT.
Posted: Thu Oct 26, 2006 9:51 am
by robert
Hi wdelaney72,
regarding the Assclown-builders: obviously George doesn't like goop as much as Howie did in his 7umble amps...
Regards
Robert
Posted: Thu Oct 26, 2006 11:51 am
by wdelaney72
I'm sure George can find a good deal on some black epoxy.