The thought came into my head, what if you had 2 transformers say they're both line level primaries and the secondaries are 6V @ 1A and 12V @ 1A. If you connect the secondaries in parallel, what is your resulting voltage and rating? I'd guess 9V, but I have no idea on the rating.
1
-
1\$\begingroup\$ From first hand experience: one of the transformers will burn-out. \$\endgroup\$– MarkCommented May 29, 2016 at 3:59
Add a comment
|
2 Answers
\$\begingroup\$
\$\endgroup\$
If you used equal value resistors (say 5 ohm in value) to connect the two transformer outputs then the junction of the two resistors would indeed be 9V RMS with respect to the common secondary terminal. Unfortunately in doing so you are using nearly all the available energy that the transformers can supply but if this is for a low power application you can do it. You could also do it with any equal value resistors but don't go lower than 3 ohms or you'll be exceeding the current output on the secondaries and they will start to get quite warm.
Low power applications fine, rated power applications not so fine.
\$\begingroup\$
\$\endgroup\$
If you connect everything in phase, the result will be as shown by the upper trace, with R1 and R3 representing the secondary winding resistances of T1 and T2.
If you connect one of the secondaries out of phase, however, the secondaries will effectively be in series and the current through them will be as shown by the lower trace.
The LTspice circuit list is included after the graphic just in case you want to play with the circuit.
Version 4
SHEET 1 992 740
WIRE -1120 -384 -1232 -384
WIRE -992 -384 -1040 -384
WIRE -816 -384 -912 -384
WIRE -688 -384 -736 -384
WIRE -496 -384 -608 -384
WIRE -1232 -352 -1232 -384
WIRE -1120 -352 -1120 -384
WIRE -1040 -352 -1040 -384
WIRE -688 -352 -688 -384
WIRE -608 -352 -608 -384
WIRE -496 -352 -496 -384
WIRE -1088 -272 -1088 -352
WIRE -1072 -272 -1072 -352
WIRE -656 -272 -656 -352
WIRE -640 -272 -640 -352
WIRE -1232 -240 -1232 -272
WIRE -1120 -240 -1120 -272
WIRE -1120 -240 -1232 -240
WIRE -608 -240 -608 -272
WIRE -496 -240 -496 -272
WIRE -496 -240 -608 -240
WIRE -1232 -224 -1232 -240
WIRE -496 -224 -496 -240
WIRE -1040 -208 -1040 -272
WIRE -688 -208 -688 -272
WIRE -1232 -112 -1232 -144
WIRE -496 -112 -496 -144
WIRE -1120 0 -1232 0
WIRE -992 0 -1040 0
WIRE -816 0 -912 0
WIRE -688 0 -736 0
WIRE -496 0 -608 0
WIRE -1232 32 -1232 0
WIRE -1120 32 -1120 0
WIRE -1040 32 -1040 0
WIRE -688 32 -688 0
WIRE -608 32 -608 0
WIRE -496 32 -496 0
WIRE -1088 112 -1088 32
WIRE -1072 112 -1072 32
WIRE -656 112 -656 32
WIRE -640 112 -640 32
WIRE -1232 144 -1232 112
WIRE -1120 144 -1120 112
WIRE -1120 144 -1232 144
WIRE -608 144 -608 112
WIRE -496 144 -496 112
WIRE -496 144 -608 144
WIRE -1232 160 -1232 144
WIRE -496 160 -496 144
WIRE -1040 176 -1040 112
WIRE -688 176 -688 112
WIRE -1232 272 -1232 240
WIRE -496 272 -496 240
FLAG -1232 -112 0
FLAG -1040 -208 0
FLAG -496 -112 0
FLAG -688 -208 0
FLAG -1232 272 0
FLAG -1040 176 0
FLAG -496 272 0
FLAG -688 176 0
SYMBOL ind2 -1136 -256 M180
WINDOW 0 -33 73 Left 2
WINDOW 3 -29 39 Left 2
SYMATTR InstName L1
SYMATTR Value 3
SYMATTR Type ind
SYMATTR SpiceLine Rser=1
SYMBOL ind2 -1024 -256 R180
WINDOW 0 -42 65 Left 2
WINDOW 3 -56 40 Left 2
SYMATTR InstName L2
SYMATTR Value 30m
SYMATTR Type ind
SYMBOL voltage -1232 -368 R0
WINDOW 3 24 96 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value SINE(0 170 50)
SYMATTR InstName V1
SYMBOL res -1248 -240 R0
WINDOW 0 48 39 Left 2
WINDOW 3 40 64 Left 2
SYMATTR InstName RS1
SYMATTR Value 1meg
SYMBOL ind2 -592 -256 R180
WINDOW 0 -33 73 Left 2
WINDOW 3 -29 39 Left 2
SYMATTR InstName L3
SYMATTR Value 3
SYMATTR Type ind
SYMATTR SpiceLine Rser=1
SYMBOL ind2 -704 -256 M180
WINDOW 0 -42 65 Left 2
WINDOW 3 -56 40 Left 2
SYMATTR InstName L4
SYMATTR Value 7.5m
SYMATTR Type ind
SYMBOL voltage -496 -368 M0
WINDOW 3 24 96 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value SINE(0 170 50)
SYMATTR InstName V2
SYMBOL res -480 -240 M0
WINDOW 0 48 39 Left 2
WINDOW 3 40 64 Left 2
SYMATTR InstName RS2
SYMATTR Value 1meg
SYMBOL ind2 -1136 128 M180
WINDOW 0 -33 73 Left 2
WINDOW 3 -29 39 Left 2
SYMATTR InstName L5
SYMATTR Value 3
SYMATTR Type ind
SYMATTR SpiceLine Rser=1
SYMBOL ind2 -1024 128 R180
WINDOW 0 -42 65 Left 2
WINDOW 3 -56 40 Left 2
SYMATTR InstName L6
SYMATTR Value 30m
SYMATTR Type ind
SYMBOL voltage -1232 16 R0
WINDOW 3 24 96 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value SINE(0 170 50)
SYMATTR InstName V3
SYMBOL res -1248 144 R0
WINDOW 0 48 39 Left 2
WINDOW 3 40 64 Left 2
SYMATTR InstName RS3
SYMATTR Value 1meg
SYMBOL ind2 -592 128 R180
WINDOW 0 -33 73 Left 2
WINDOW 3 -29 39 Left 2
SYMATTR InstName L7
SYMATTR Value 3
SYMATTR Type ind
SYMATTR SpiceLine Rser=1
SYMBOL ind2 -704 16 R0
WINDOW 0 -37 38 Left 2
WINDOW 3 -52 65 Left 2
SYMATTR InstName L8
SYMATTR Value 7.5m
SYMATTR Type ind
SYMBOL voltage -496 16 M0
WINDOW 3 24 96 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value SINE(0 170 50)
SYMATTR InstName V4
SYMBOL res -480 144 M0
WINDOW 0 48 39 Left 2
WINDOW 3 40 64 Left 2
SYMATTR InstName RS4
SYMATTR Value 1meg
SYMBOL res -896 -400 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 1
SYMBOL res -896 -16 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R4
SYMATTR Value 1
SYMBOL res -720 -400 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 1
SYMBOL res -720 -16 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R6
SYMATTR Value 1
TEXT -1136 -424 Left 2 !K1 L1 L2 1
TEXT -1224 -136 Left 2 !.tran .1 uic
TEXT -592 -424 Right 2 !K2 L3 L4 1
TEXT -1136 -40 Left 2 !K3 L5 L6 1
TEXT -592 -40 Right 2 !K4 L7 L8 1
TEXT -1096 -376 Left 2 ;TI
TEXT -656 -376 Left 2 ;T2
TEXT -1088 8 Left 2 ;T3
TEXT -656 8 Left 2 ;T4
answered May 29, 2016 at 12:06