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    10A or 20A Bucker Transformer for M125's?

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    cci1492

    Posts : 160
    Join date : 2016-05-09
    Age : 57
    Location : Bergen County NJ

    Re: 10A or 20A Bucker Transformer for M125's?

    Post by cci1492 on Fri Apr 13, 2018 8:40 am

    Thanks! Just order it from Digi-Key, did a little more looking around and concluded the 6.3 TA will do the trick for the reason you stated. Also ordered a couple of inrush current limiters (30A) for the Vairac. Looks like the breaker is tripped because of the sudden current surge when powering up. Intermittent because it depends where the sinusoidal wave form is at when the switch is thrown. At times the current I measured is 0 (when switch thrown), other times between 2 and 3Amps., other times 9A, and this is with no load at all on output of the Variac. The Variac behaves just fine once it's on and didn't trip the breaker. With no load it sits at .08A, it handles just fine loads in excess of 13A with ease. Took it apart, built nicely and clean. I just think it's a beast and needs a soft start of sorts to not trip breakers. I think Square D makes a breaker for this purpose but not going that route for now.
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    Dave_in_Va

    Posts : 225
    Join date : 2013-04-02

    Re: 10A or 20A Bucker Transformer for M125's?

    Post by Dave_in_Va on Fri Apr 13, 2018 9:44 am

    I post this link every time this subject comes up.
    The simple one will do the trick, in fact mine are even simpler as I couldn't foresee the use of a 12% voltage reduction. I just shrink wrapped those leads.

    https://robrobinette.com/5e3_Modifications.htm#Bucking_Transformer

    Right now I measure 122.6 out of the wall and 115.5 out of the bucker. Close enough, I think.
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    gktamps

    Posts : 14
    Join date : 2017-07-30
    Location : Santa Rosa, CA

    Re: 10A or 20A Bucker Transformer for M125's?

    Post by gktamps on Fri Apr 13, 2018 10:42 am

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    LeGrace

    Posts : 252
    Join date : 2016-08-07
    Location : Ontario, Canada

    Re: 10A or 20A Bucker Transformer for M125's?

    Post by LeGrace on Fri Apr 13, 2018 11:21 am

    Mine is also simpler. No lights, switches, or fuses. Just a single 2 plug outlet along with the transformer. And connecting only the lower output leads. Nice compact little box that is easy to tuck out of the way.

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    Re: 10A or 20A Bucker Transformer for M125's?

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