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Hoffman Amps Forum image Author Topic: Everyday I discover something new (to me) - Selmer 25U Phase Inverter ???  (Read 1940 times)

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Offline kagliostro

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I had under the eyes lot of times the Selmer schematics and always in my mind the PI in the T2U and 25U were archived as Transformer Phase Inverters

few minutes ago I was astonished seeng that the PI isn't a transformer, in the schematic it is indicated as a coil with an intake (50% I think)

Can someone explain how that can act as a PI ?

There are other amps with this architecture ?

Is possible to find documentation about those kind of coils ?






Many Thanks

Franco
« Last Edit: December 02, 2022, 04:29:29 pm by kagliostro »
The world is a nice place if there is health and there are friends

Offline sluckey

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Re: Everyday I discover something new (to me) - Selmer 25U Phase Inverter ???
« Reply #1 on: December 02, 2022, 05:11:54 pm »
The coil is an autotransformer.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline PRR

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Re: Everyday I discover something new (to me) - Selmer 25U Phase Inverter ???
« Reply #2 on: December 02, 2022, 06:01:48 pm »
Specifically a Center-Tapped autotransformer.

You can fake it with a high-impedance push-pull transformer primary.

Radiotron Designers Handbook 4th, page 522. (I think the text in (C) is wrong.)
« Last Edit: December 02, 2022, 06:06:17 pm by PRR »

Offline kagliostro

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Re: Everyday I discover something new (to me) - Selmer 25U Phase Inverter ???
« Reply #3 on: December 02, 2022, 06:27:10 pm »
Many Thanks Sluckey & PRR



Franco
The world is a nice place if there is health and there are friends

 


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