EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: SashPlane on November 21, 2024, 06:12:20 pm
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Hello,
I'm looking for help with what TR5 and TR6 are doing. I'm not quite sure as what they do ?? The Problem is TR5 BF 487 has gone Obsolete and we can no longer get.
I tried a MPSA44 but it does not work like the BF487. When you use the MPSA44 , R41 Gets Supper Dupper HOT(Technical Term) SMPS works but TR5 HOT
the BF487 had a gain of Aprox 50 ish , the MPSA gain of 1
Input voltage is 90 - 260 vac , outputs: 5v and 12v
Thanks for any help :)
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Tr5 and tr6 are making a linear regulator to supply the controller IC. You should be able to substitute anything with similar voltage and power rating and gains. The current won't be very high.
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For an undamaged MPSA44 to have a current gain of 1, is likely due to E and C being swapped.
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OH Man...... you nailed it |O
Now I feel like a Co-op again....lol
Thanks a bunch :) :-+
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Hi!
Let me be curious: who drew such a proper diagram with common bus wiring?
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this drawing was done long before I took over this...
the original was Hand drawn on vellum and then later converted to PDF.
I still even have the Vellum PWB @ 4x F Size Artwork layout... of course i also have it converted to Gerber now also.
Tape layout with stick-on pads - Good ole days of layout
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I have not yet seen that the current sense resistor at MOSFET source being bypassed by a capacitor.
Is it possible to obtain traces from the current sense resistor at maximum load with C28 capacitor and without it?
PS
Do you have any transformer data? Dimensions, core material, air gap?