I'm going to build another Princeton because I like the first one I made so much, and that one is headed to a friend soon. I was looking at "upgraded" Princeton PT transformers and wondered if anyone has built a Princeton circuit using a dual PT secondary like this one? I thought I could put the two secondaries on a DPDT switch with a center-off for a standby option.
https://www.hammfg.com/files/parts/pdf/291AEX.pdf
BF PRINCETON with dual PT secondary?
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BF PRINCETON with dual PT secondary?
Just plug it in, man.
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Stevem
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Re: BF PRINCETON with dual PT secondary?
Yes a DPDT switch will allow you to place both windings in parallel to have the US / 120 volt setting which is the way it's done.
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Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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sluckey
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2 others liked this
Re: BF PRINCETON with dual PT secondary?
He's not asking about the primaries. He's asking about switching the dual taps on the HT secondary to provide either 325-0-325 or 275-0-275 to the rectifier.
Yes, you can do that, but you may want to check the bias every time you switch. Not worth the effort IMO. Such a switch could be more useful with cathode biased output tubes. I would just experiment and find the secondary taps that you prefer and tape off the other taps.
Yes, you can do that, but you may want to check the bias every time you switch. Not worth the effort IMO. Such a switch could be more useful with cathode biased output tubes. I would just experiment and find the secondary taps that you prefer and tape off the other taps.
Re: BF PRINCETON with dual PT secondary?
Assuming you're building a cathode biased Princeton, my first thought about that PT is to use solid state diodes on the 275V taps to get ~385V on the plates and a tube rectifier on the 325V taps to get closer to 300V on the plates. Those are the plate voltage targets that look good to me using that PT anyway.
However, if you're especially happy with the last Princeton you built and want to recreate that, you'll be better off aiming for the same plate voltage target as the one you know you like.
However, if you're especially happy with the last Princeton you built and want to recreate that, you'll be better off aiming for the same plate voltage target as the one you know you like.
Re: BF PRINCETON with dual PT secondary?
That sounds interesting. I wasn't planning on cathode-biasing the power tubes, but I can see how that would make sense. I'm not exactly sure how I would design that. I can also see how cool it would be to have a tube-rectified and a SS-rectified option on tap with their own bias settings. That could very well be over my head at present, though. I tested a Marshall-style build with just switching the HT secondary into the same fixed bias circuit and it did sound good and different, but it was clear it needed more refining. We'll see.
Just plug it in, man.