heater current question

wireball · 10-21-2006, 02:39 AM

Hey guys, if I use one side of a 12a-7, and figure out
which of heater pins 4 or 5 operate in that section. Then, operate
that heater at 6.3v, how much current will it draw? .3A or .15 A?

Enzo · 10-21-2006, 03:20 AM

Current is the same throughout a series circuit. The .15A in the 12v arrangement doesn't change when you consider only half. All the 12v arrangement is is two 6v heaters in series, each drawing .15A - the SAME .15A flows through both. In parallel across 6v, EACH side draws its own .15A, whuch in parallel adds to .3A.

wireball · 10-21-2006, 07:31 AM

Enzo, hello! Thank you once again for your help, I know it's
a basic question. Though I have built many amps, I didn't know
the answer to that one. It's never mentioned in any of the
tube data, and I could not find it in any of the many books I have.

I posted this question about a year ago and received two conflicting
answers.

I guess that's the reason it's not mentioned in the tube data.
No sense in being redundant, silly me.

10-21-2006, 02:39 AM	#1
wireball Junior Member Join Date: Sep 2006 Location: Ca Posts: 15	heater current question Hey guys, if I use one side of a 12a-7, and figure out which of heater pins 4 or 5 operate in that section. Then, operate that heater at 6.3v, how much current will it draw? .3A or .15 A?

10-21-2006, 07:31 AM	#3
wireball Junior Member Join Date: Sep 2006 Location: Ca Posts: 15	heater current question Enzo, hello! Thank you once again for your help, I know it's a basic question. Though I have built many amps, I didn't know the answer to that one. It's never mentioned in any of the tube data, and I could not find it in any of the many books I have. I posted this question about a year ago and received two conflicting answers. I guess that's the reason it's not mentioned in the tube data. No sense in being redundant, silly me.

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10-21-2006, 03:20 AM	#2
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 10,366	Current is the same throughout a series circuit. The .15A in the 12v arrangement doesn't change when you consider only half. All the 12v arrangement is is two 6v heaters in series, each drawing .15A - the SAME .15A flows through both. In parallel across 6v, EACH side draws its own .15A, whuch in parallel adds to .3A.

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