Running two PT secondary taps in series?

[joesatch]

Can i run these two 6.3vac secondaries in series to get 12.6vac?  Will this cause a house fire?

[thetragichero]

you'll have to make sure to wire in phase otherwise you'll add 6.3v and 6.3v and end up with 0v

do you have a link to that transformer? that would work as replacement to a 217vac/12.6vac toroid i've used that's no longer available

[joesatch]

do you have a link to that transformer? that would work as replacement to a 217vac/12.6vac toroid i've used that's no longer available

like this? What is the result in volts, amps?



https://www.antekinc.com/as-05t200-50va-200v-transformer/

[tubeswell]

Yes, like ^that^ 12.6V 2A

[joesatch]

if i ran the 12.6v through a FWB what would be the DC voltage?

[shooter]

guessing around 17-18v un-loaded out of the bridge

[joesatch]

for 12vdc heaters would you use dropping resistors after the fwb or incorporate a voltage regulator to get it to 12vdc?

[shooter]

when I build a PS for some need, I decide if I need regulated or just close.
I put FIL in the just close box
so I put a CRC after the bridge, then calculate the current load for my need.
then I calculate a "dummy load" resistor to simulate my need.  wire it up, and make measurements.
from there I decide if it's close enough, needs tweaking, or back to the drawing board.

[joesatch]

voltage regulator it is!
 

https://www.mouser.com/ProductDetail/STMicroelectronics/L7812CV?qs=5Uvc6lfWVJzVGZQZmBynyg%3D%3D

[uki]

voltage regulator it is!

Output current up to 1.5 A

Will it be enough?

[joesatch]

ya i'm powering (3) 12ax7

[TIMBO]

OR....
Voltage doubler on one winding....

[glass54]

Hi joesatch,
I have done DC supplies for ECC83/12AX7 on a number of occasions (in preamps). See attached pix.
I suggest an LM7812T with a diode on GRD terminal to give you 12.55V DC nominal.
You said 3 off 12AX7 requiring approx 150mA per tube 12.5V DC, so 3 tubes would require a little less than 500mA.
Shooter correctly approximated 17V to 18V DC from your 12.6V AC transformer taps.
The main reason I'm pitching in is that your LM7812T may need a heatsink, as say 17.5V -12.5V gives around 5V at approx 500mA comes in just under 2.5W. Shouldn't be a big problem, doesn't have to be big, but you need to secure it in the chassis.
I suggest 2.5W is quite warm and gets worse if you increase number of tubes.
Regards
Mirek