Well spotted- the AC inputs should each see one kathode and one anode, and the positive output should be 2 kathodes, and the negative output should be 2 anodes.


The  data sheet for the rectifier indicates it is a 25 amp part, rated at  a mere 200v for reverse breakdown.  A rectifier rating of 25A forward feels like overkill, given what you said about the wire sizes, though that rating assumes you have it on a 25 degree C cold plate. However the 200V reverse, (noting a 110V RMS is more like 145v pk) seems to leave very little margin for the sort of 'flash and pop' surges often seen when contacts close on motor shuddering to a halt.  (the data sheet notes that 140V RMS is the limit for the 200V part.) However, if it passes the 'am I a diode' tests with the meter, then you are OK to keep it in there. (there are plenty of similar parts made of varying ratings  examples of bridges from the CPC catalogue. )



The current rating of wire when wound into a transformer is a funny function of the wire packing density, and its ability to cool via conduction through the rest of the winding, and the fact that the skin depth is far more serious than normal, because the magnetic field vs current is higher than the free space case. However the key thing is that the BS7671 wire rating values are miles off.

Luckily others have done the work for us , and there is a good reference for wire size versus cu rent in winding for low power 50Hz mains transformers here,  though in summary about 3-4 A per mm2 seems about right and if your wire sizes are  CSA in  mm2, then suggests only an amp or 2 for the windings you have. (I did say the BS7671 values were miles out for transformers didn't I..) This is more like 250VA, so not fitting that well with the 4 kilo weight. It may never have been fully optimised, if it predated CAD, that is quite likely.

Indeed if you are very brave, his "how to roll your own" article from the same website is very informative too see here.  Nowadays I only would only ever countenance this if I had a need to replace some special part for for some very odd voltage, as life is too short, and there are plenty of transformers in the catalogues, but I remember winding replacement transformer of a couple of hundred watts  with about ten secondaries to restore an oscilloscope many years ago, and it taking forever (probably about 2 weeks of evenings) just to wind the thing. I have used a lathe on freewheel as a manual winding machine, but even so it quickly gets painful, and hand winding never seems to manage to get quite as many turns in as the original manufactured item.

Well spotted- the AC inputs should each see one kathode and one anode, and the positive output should be 2 kathodes, and the negative output should be 2 anodes.


The  data sheet for the rectifier indicates it is a 25 amp part, rated at  a mere 200v for reverse breakdown.  A rectifier rating of 25A forward feels like overkill, given what you said about the wire sizes, though that rating assumes you have it on a 25 degree C cold plate. However the 200V reverse, (noting a 110V RMS is more like 145v pk) seems to leave very little margin for the sort of 'flash and pop' surges often seen when contacts close on motor shuddering to a halt.  (the data sheet notes that 140V RMS is the limit for the 200V part.) However, if it passes the 'am I a diode' tests with the meter, then you are OK to keep it in there. (there are plenty of similar parts made of varying ratings  examples of bridges from the CPC catalogue. )



The current rating of wire when wound into a transformer is a funny function of the wire packing density, and its ability to cool via conduction through the rest of the winding, and the fact that the skin depth is far more serious than normal, because the magnetic field vs current is higher than the free space case. However the key thing is that the BS7671 wire rating values are miles off.

Luckily others have done the work for us , and there is a good reference for wire size versus cu rent in winding for low power 50Hz mains transformers here,  though in summary about 3-4 A per mm2 seems about right and if your wire sizes are  CSA in  mm2, then suggests only an amp or 2 for the windings you have. (I did say the BS7671 values were miles out for transformers didn't I..) This is more like 250VA, so not fitting that well with the 4 kilo weight. It may never have been fully optimised, if it predated CAD, that is quite likely.

Indeed if you are very brave, his "how to roll your own" article from the same website is very informative too see here.  Nowadays I only would only ever countenance this if I had a need to replace some special part for for some very odd voltage, as life is too short, and there are plenty of transformers in the catalogues, but I remember winding replacement transformer of a couple of hundred watts  with about ten secondaries to restore an oscilloscope many years ago, and it taking forever (probably about 2 weeks of evenings) just to wind the thing. I have used a lathe on freewheel as a manual winding machine, but even so it quickly gets painful, and hand winding never seems to manage to get quite as many turns in as the original manufactured item.