Sunday, April 3, 2016

a fuzzy science on old transformers

By the time it's gathered here a pile of transformers from the PC speakers , cordless & cell-phone loaders , modems , routers , X-mas lights , e.c. - some of which have their primary's overheating/over-current protections blown , for some i have replaced the 2-ry multiple or too low voltage windings with a single new 1 ...

the following table is apx. accurate within (more...less) ±...25...33... % which i find sufficient describing the multitude of transformers from different manufacturers and possible evolved...recovered fault conditions

the fuzzy science :: we find -
the lab./stat. avg. impedance of the 1-ry winding (2-ry open = apx.1MΩ(Vm))
the lab./stat. avg. voltage transfer ratio (2-ry open = apx.1MΩ(Vm))
the output voltage mutiplier for the rectified 2-ry voltage (2-ry open = apx.1MΩ(Vm))
the output voltage degrading coefficient for the rectified 2-ry voltage with load (25...330 Ω , 47uF filter)
the estimate (based on above) for 1...10k Ω loading of the rectified , filtered output (on the 2-ry winding)

so the table list below rectified , filtered DC voltage values estimates against the load resistance :
the percentage (parenthed) = P.OUT / (P.IN - P.OUT) @ est.-d  P.OUT.Max

the .CC is operational Nokia (Type: ACP-7E) 3.7V cellphone charger´s TF
.C10 is ® while .C60 , .C70 and .230 have the replaced 2-ries
.ZHN28 is from the incandescent X-mas lights rectifier from China


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