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Old 19th February 2006, 10:33 AM   #1
Jaap is online now Jaap  Netherlands
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Question power transformers in series

If I put two transformers in series that each can deliver 100 mA, can I then take 200 mA from the pair ?
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Old 19th February 2006, 10:43 AM   #2
alex278 is offline alex278  Netherlands
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Approximately, yes. However, if one of the tansformers delivers slightly less voltage than the other, or behaves differently when loaded, the other transformer will sink some current in the 'different' transformer. So I would be very careful.

(and remember that you'll need to have the phases of the windings correct, or otherwise you'll have an instant short-circuit)
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Old 19th February 2006, 11:00 AM   #3
Tweeker is offline Tweeker  United States
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Would you not get double the voltage, not double the current running them in series?

Perhaps you mean in parallel, where the above comments would apply?
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Old 19th February 2006, 11:05 AM   #4
jeapel is offline jeapel  Canada
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hi

200ma with 2 transfo = parallel not serie

and you need 2 exactly identical transfo

and double check phase like alex278 said

but maybe the best solution if you have

2 transfo would be 2 power supply with better channel

seperation for better stereo image

bye
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Old 19th February 2006, 11:05 AM   #5
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Nope.

Series doubles voltages, not current. Actually, due to I2R losses, the current will probably be 0.95 times that of one unit (ref: Hammond data sheet)

Parallel doubles current while voltage remains the same.
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Old 19th February 2006, 11:31 AM   #6
Jaap is online now Jaap  Netherlands
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Default now I understand

why I can fry an egg on the transformers. I will set them parallel and will a take another circuit to get the needed voltage (scottky diode + tube rectifier in a bridge, omitting the center tap).
Thanks guys !
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Old 19th February 2006, 11:45 AM   #7
jeapel is offline jeapel  Canada
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scottky diode ? are 40volt max. after it s a short circuit

but send a schematic to understand your design

but now turn off :-) your power supply because

transfo are very $$
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Old 19th February 2006, 11:50 AM   #8
Jaap is online now Jaap  Netherlands
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I will use BYW96e
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Old 19th February 2006, 03:28 PM   #9
jeapel is offline jeapel  Canada
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ok it s not a schottky diode but a 1000volt diode

test :

1-take just 1 transfo +BYW96E bridge +tube diode(for turn on
delay if i understand)
2-without load check temp after 1 hour (max. 40 to 50 C )
3-if ok try maybe 25ma after 50ma after 75ma to find the
max load for 1 transfo
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Old 19th February 2006, 06:23 PM   #10
Jaap is online now Jaap  Netherlands
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The circuit of the diodes is the same as in this attached file. It is a nice solution if you do not have a centertap on your transformer. I found this solution in a magazine that is about 50 years old and you can still use it for free
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File Type: gif se_psucuff.gif (32.2 KB, 114 views)
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