Wiring LED pilot off of 5 vac / using CT off of 6.3 vac supply of PT

[MonoPoly]

Hi, I'm building a Hoffman AB763 with quirky layout. I have two questions that are related, but it's probably unnecessary and too time consuming to explain why.

Q1: I should be fine grabbing 5 vac from pins 2 and 8 of rectifier socket for an LED pilot light in series with a current limiting resistor, right? PT is rated for 3 amps, current plan is to use 5ar4 drawing 2 amps. Even if I decide to drop the B+ with a 5u4 (draws 3 amps) - would the ~15 ma the LED draws be inconsequential? I guess the LED would flicker 60 times a second, but that's over two and half times the frame rate of Citizen Kane.

Q2: My PT's 6.3 supply has a center tap and I'm thinking of using that instead of the artificial center tap on the turret board (those two 100ohm resistors to ground). It means having about 8-10 less inches of AC wire in the amp. I also read that in the case of certain power tube shorts while the fuse doesn't blow quick enough: if the PT CT is used, it means frying the PT, while if the artificial CT is used, it means frying the tubes.

[sluckey]

Q1... Don't do it.

Q2... Do it.

[ac427v]

Thinking of my next silicon rectified build. What about the unused 5 volt rectifier winding to power a standard 6.3 volt indicator bulb? That would eliminate the usual wiring from the bulb socket to the first power tube heaters.

[sluckey]

Thinking of my next silicon rectified build. What about the unused 5 volt rectifier winding to power a standard 6.3 volt indicator bulb? That would eliminate the usual wiring from the bulb socket to the first power tube heaters.

That's fine.

[Williamblake]

Dont do it plus one. Taking LED supply voltage from the heater winding gives nasty flicker.

[PRR]

> grabbing 5 vac from pins 2 and 8 of rectifier socket for an LED pilot

The pilot light is normally within 10V, certainly 100V, of ground. But rectifier heater can be 500 volts away from ground. Nobody expects a LED pilot light to be lethal high tension.

[MonoPoly]

Thanks for the replies -- otherwise hopefully I would have realized the 5 vac has B+ on it when connecting pin 8 with the filter caps, choke, and CT of OT.

Is "volts away from ground" the same as "neutral to earth voltage"?

I'll hook my LED up off the 6.3 vac as Mr. Hoffman illustrates here: https://el34world.com/Forum/index.php?topic=12842.msg119830#msg119830

[sluckey]