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Hoffman Amps Forum image Author Topic: Artificial Center Tap Resistor Question  (Read 3225 times)

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Offline imgumby001

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Artificial Center Tap Resistor Question
« on: December 02, 2020, 12:22:49 pm »
I need to create an artificial 6.3 center tap on my current build and I don’t have any 1/2w 100ohm resistors, I’ve got a bunch of 1/4w. Is it dangerous to go that low? Will they just blow out?

Thx

Offline pdf64

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Re: Artificial Center Tap Resistor Question
« Reply #1 on: December 02, 2020, 01:14:38 pm »
The arithmetic is simple,
Power = voltage squared / resistance
So 6.3 x 6.3 =40
40 / 200 = 0.2W
That’s 0.1W per 100 ohm resistor.

Personally I used 5W, as in the case of s power tube fault shorting HT current to the heater circuit, I prefer them to hold and blow a fuse.
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Offline imgumby001

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Re: Artificial Center Tap Resistor Question
« Reply #2 on: December 02, 2020, 01:18:49 pm »
The arithmetic is simple,
Power = voltage squared / resistance
So 6.3 x 6.3 =40
40 / 200 = 0.2W
That’s 0.1W per 100 ohm resistor.

Personally I used 5W, as in the case of s power tube fault shorting HT current to the heater circuit, I prefer them to hold and blow a fuse.

Thanks pdf. The math is what I need more than anything. Knowing where to apply it always alludes me. Looks like I’m taking a trip to radio shack!! Good thing we STILL have one out here in B.F.E.

Offline Latole

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Re: Artificial Center Tap Resistor Question
« Reply #3 on: December 02, 2020, 01:23:21 pm »
Some amp use 47 ohms 1/2 watts , other use 200 ohms 1/2 watts.  You many choice.
http://www.valvewizard.co.uk/heater.html
« Last Edit: December 02, 2020, 01:27:02 pm by Latole »

Offline imgumby001

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Re: Artificial Center Tap Resistor Question
« Reply #4 on: December 02, 2020, 02:38:51 pm »
Some amp use 47 ohms 1/2 watts , other use 200 ohms 1/2 watts.  You many choice.
http://www.valvewizard.co.uk/heater.html

Thanks latole. I just went out and picked up some 100ohm 1/2 watters. It’s about 30min away, but it gave me the opportunity to upgrade my channel switch. I’m hemorrhaging money on this deal. Gotta love it!!

 


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