Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: shooter on November 01, 2013, 05:14:31 pm

Title: Impractical question
Post by: shooter on November 01, 2013, 05:14:31 pm
Can I take 2 identical P.T.’s and wire the HT windings in series ? ( Driving higher voltage power tubes is the reason case anyone was scratchin heads, n i'm well versed in death by electricution :icon_biggrin:).

Thanks guys

dave
Title: Re: Impractical question
Post by: sluckey on November 01, 2013, 05:23:06 pm
yes
Title: Re: Impractical question
Post by: kagliostro on November 02, 2013, 02:42:07 am
You can put the AC winding in series and then rectify the two extremities of the result
[consider the joint between the two windings as a sort of CT (don't connect this to anything)]

or you can rectify each winding separately and stack the bridges connecting the - (minus) of one diode bridge to the + (plus) of the other bridge (see the MIG60 schematic I've posted in the forum few days ago)

http://www.el34world.com/Forum/index.php?action=dlattach;topic=16229.0;attach=39591;image (http://www.el34world.com/Forum/index.php?action=dlattach;topic=16229.0;attach=39591;image)

this way you can use electrolytic caps rated for a lower voltage

K
Title: Re: Impractical question
Post by: shooter on November 02, 2013, 12:45:54 pm
So now that i can series them...when you series up caps i know they act like R's in parallel for capacitance, what happens to cap volts rating, 500V in series with 500V yeilds 250 or 1000v?
Thanks again for the help

dave
Title: Re: Impractical question
Post by: eleventeen on November 02, 2013, 01:24:11 pm
Provided the two windings are in phase, they will add. Wire up the primaries and connect one wire of each secondary together. Power up and measure volts between the UNconnected sec. wires. Have your meter on maximum voltage range if it is not autoranging. If out of phase (and the trannies are identical) you'll get (theoretically) zero volts but in any event, a very low volt reading. If so, change ONLY ONE wire at the junction point. Do this with alligator clips on your test leads or wrap the stripped ends of the to-be-measured wires around your meter probes. Don't play games with this, if you have a couple of 200 volt windings in series, ostensibly not enough for amp purposes, unloaded, they could produce as much as 600 volts and 300 volts * 2 could get up near 1 Kv.

Not that you'd want to be shocked with 200 volts...but be aware that the two windings in series could produce some very high volts.
Title: Re: Impractical question
Post by: sluckey on November 02, 2013, 01:46:54 pm
Quote
what happens to cap volts rating, 500V in series with 500V yeilds 250 or 1000v?
1000v