Power Transformer: 110V and 220V input, with two 15V outputs 180 degrees out of phase

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I have never designed a power supply before and have a few questions and would appreciate any help.



  • Firstly, I want to use a transformer that can both take 220V and 110V inputs. Can I use a center tap transformer and for 110V put the coils in series and for 220V only use one coil and leave the second open circuited?


  • Secondly, I need an output of + and - 15, so do I select a transformer with a center tap secondary and wire the two identical outputs to be 180 degrees out of phase?


  • Lastly, I cannot find any transformers with these specifications. What I've been looking for is a center tap primary and secondary with a ratio of 15:1


Thank you in advance.










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  • 1




    Is that 15V AC or DC? And does it need to be isolated?
    – ratchet freak
    16 hours ago







  • 1




    A centre tapped transformer CANNOT be rewired as you seem to be implying.
    – Andy aka
    16 hours ago














up vote
6
down vote

favorite












I have never designed a power supply before and have a few questions and would appreciate any help.



  • Firstly, I want to use a transformer that can both take 220V and 110V inputs. Can I use a center tap transformer and for 110V put the coils in series and for 220V only use one coil and leave the second open circuited?


  • Secondly, I need an output of + and - 15, so do I select a transformer with a center tap secondary and wire the two identical outputs to be 180 degrees out of phase?


  • Lastly, I cannot find any transformers with these specifications. What I've been looking for is a center tap primary and secondary with a ratio of 15:1


Thank you in advance.










share|improve this question









New contributor




Andre Faraday is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.















  • 1




    Is that 15V AC or DC? And does it need to be isolated?
    – ratchet freak
    16 hours ago







  • 1




    A centre tapped transformer CANNOT be rewired as you seem to be implying.
    – Andy aka
    16 hours ago












up vote
6
down vote

favorite









up vote
6
down vote

favorite











I have never designed a power supply before and have a few questions and would appreciate any help.



  • Firstly, I want to use a transformer that can both take 220V and 110V inputs. Can I use a center tap transformer and for 110V put the coils in series and for 220V only use one coil and leave the second open circuited?


  • Secondly, I need an output of + and - 15, so do I select a transformer with a center tap secondary and wire the two identical outputs to be 180 degrees out of phase?


  • Lastly, I cannot find any transformers with these specifications. What I've been looking for is a center tap primary and secondary with a ratio of 15:1


Thank you in advance.










share|improve this question









New contributor




Andre Faraday is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











I have never designed a power supply before and have a few questions and would appreciate any help.



  • Firstly, I want to use a transformer that can both take 220V and 110V inputs. Can I use a center tap transformer and for 110V put the coils in series and for 220V only use one coil and leave the second open circuited?


  • Secondly, I need an output of + and - 15, so do I select a transformer with a center tap secondary and wire the two identical outputs to be 180 degrees out of phase?


  • Lastly, I cannot find any transformers with these specifications. What I've been looking for is a center tap primary and secondary with a ratio of 15:1


Thank you in advance.







power transformer






share|improve this question









New contributor




Andre Faraday is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question









New contributor




Andre Faraday is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









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edited 15 hours ago









SamGibson

10.6k41537




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Check out our Code of Conduct.









asked 16 hours ago









Andre Faraday

333




333




New contributor




Andre Faraday is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





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Andre Faraday is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






Andre Faraday is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







  • 1




    Is that 15V AC or DC? And does it need to be isolated?
    – ratchet freak
    16 hours ago







  • 1




    A centre tapped transformer CANNOT be rewired as you seem to be implying.
    – Andy aka
    16 hours ago












  • 1




    Is that 15V AC or DC? And does it need to be isolated?
    – ratchet freak
    16 hours ago







  • 1




    A centre tapped transformer CANNOT be rewired as you seem to be implying.
    – Andy aka
    16 hours ago







1




1




Is that 15V AC or DC? And does it need to be isolated?
– ratchet freak
16 hours ago





Is that 15V AC or DC? And does it need to be isolated?
– ratchet freak
16 hours ago





1




1




A centre tapped transformer CANNOT be rewired as you seem to be implying.
– Andy aka
16 hours ago




A centre tapped transformer CANNOT be rewired as you seem to be implying.
– Andy aka
16 hours ago










2 Answers
2






active

oldest

votes

















up vote
8
down vote



accepted










Using a centre-tapped primary usually means that you de-rate the transformer to half power.



enter image description here



Figure 1. Series and parallel connections for split-winding transformer. Image source: Electro-Dan. The linked article discusses torroidal transformers but the principle is the same for standard transformers.



Instead, the common approach due to its flexibility is to use a transformer with two 110 V primaries and two equal secondaries. The primaries can then be wired in series for 220 V operation and parallel for 110 V. Similarly, the secondaries can be wired in parallel for high current or series for higher voltage. The series connection point is, in effect, the secondary centre-tap.



enter image description here



Figure 2. For switching primary voltage by the user you would add a voltage selector switch. Source: Modulus Amplification.






share|improve this answer




















  • Thank you very much! Helped a lot!
    – Andre Faraday
    14 hours ago










  • The yellow and blue is not a center tap, they are the ends of two windings. A center tap is continuous through the transformer and cannot be separated.
    – Harper
    9 hours ago

















up vote
6
down vote














Firstly, I want to use a transformer that can both take 220V and 110V inputs. Can I use a center tap transformer and for 110V put the coils in series and for 220V only use one coil and leave the second open circuited?




The normal approach is to use a transformer that has two identical primary windings, each rated for 110V and half the total transformer power. You put them in parallel for 110V operation and put them in series for 220V operation. This optimizes the amount of copper required.




Secondly, I need an output of + and - 15, so do I select a transformer with a center tap secondary and wire the two identical outputs to be 180 degrees out of phase?




If you ground the center tap, you can use the other two terminals to make separate +15V and -15V supplies. The fact that they are out of phase allows you to use full-wave rectification for both supplies.




Lastly, I cannot find any transformers with these specifications.




That would be a product recommendation, which is off-topic here.






share|improve this answer




















  • Yeah, and don't attempt to half-wave rectify them unless either your load is balanced or your transformer mount is very sturdy and well dampened :)
    – rackandboneman
    8 hours ago










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2 Answers
2






active

oldest

votes








2 Answers
2






active

oldest

votes









active

oldest

votes






active

oldest

votes








up vote
8
down vote



accepted










Using a centre-tapped primary usually means that you de-rate the transformer to half power.



enter image description here



Figure 1. Series and parallel connections for split-winding transformer. Image source: Electro-Dan. The linked article discusses torroidal transformers but the principle is the same for standard transformers.



Instead, the common approach due to its flexibility is to use a transformer with two 110 V primaries and two equal secondaries. The primaries can then be wired in series for 220 V operation and parallel for 110 V. Similarly, the secondaries can be wired in parallel for high current or series for higher voltage. The series connection point is, in effect, the secondary centre-tap.



enter image description here



Figure 2. For switching primary voltage by the user you would add a voltage selector switch. Source: Modulus Amplification.






share|improve this answer




















  • Thank you very much! Helped a lot!
    – Andre Faraday
    14 hours ago










  • The yellow and blue is not a center tap, they are the ends of two windings. A center tap is continuous through the transformer and cannot be separated.
    – Harper
    9 hours ago














up vote
8
down vote



accepted










Using a centre-tapped primary usually means that you de-rate the transformer to half power.



enter image description here



Figure 1. Series and parallel connections for split-winding transformer. Image source: Electro-Dan. The linked article discusses torroidal transformers but the principle is the same for standard transformers.



Instead, the common approach due to its flexibility is to use a transformer with two 110 V primaries and two equal secondaries. The primaries can then be wired in series for 220 V operation and parallel for 110 V. Similarly, the secondaries can be wired in parallel for high current or series for higher voltage. The series connection point is, in effect, the secondary centre-tap.



enter image description here



Figure 2. For switching primary voltage by the user you would add a voltage selector switch. Source: Modulus Amplification.






share|improve this answer




















  • Thank you very much! Helped a lot!
    – Andre Faraday
    14 hours ago










  • The yellow and blue is not a center tap, they are the ends of two windings. A center tap is continuous through the transformer and cannot be separated.
    – Harper
    9 hours ago












up vote
8
down vote



accepted







up vote
8
down vote



accepted






Using a centre-tapped primary usually means that you de-rate the transformer to half power.



enter image description here



Figure 1. Series and parallel connections for split-winding transformer. Image source: Electro-Dan. The linked article discusses torroidal transformers but the principle is the same for standard transformers.



Instead, the common approach due to its flexibility is to use a transformer with two 110 V primaries and two equal secondaries. The primaries can then be wired in series for 220 V operation and parallel for 110 V. Similarly, the secondaries can be wired in parallel for high current or series for higher voltage. The series connection point is, in effect, the secondary centre-tap.



enter image description here



Figure 2. For switching primary voltage by the user you would add a voltage selector switch. Source: Modulus Amplification.






share|improve this answer












Using a centre-tapped primary usually means that you de-rate the transformer to half power.



enter image description here



Figure 1. Series and parallel connections for split-winding transformer. Image source: Electro-Dan. The linked article discusses torroidal transformers but the principle is the same for standard transformers.



Instead, the common approach due to its flexibility is to use a transformer with two 110 V primaries and two equal secondaries. The primaries can then be wired in series for 220 V operation and parallel for 110 V. Similarly, the secondaries can be wired in parallel for high current or series for higher voltage. The series connection point is, in effect, the secondary centre-tap.



enter image description here



Figure 2. For switching primary voltage by the user you would add a voltage selector switch. Source: Modulus Amplification.







share|improve this answer












share|improve this answer



share|improve this answer










answered 16 hours ago









Transistor

77.5k577170




77.5k577170











  • Thank you very much! Helped a lot!
    – Andre Faraday
    14 hours ago










  • The yellow and blue is not a center tap, they are the ends of two windings. A center tap is continuous through the transformer and cannot be separated.
    – Harper
    9 hours ago
















  • Thank you very much! Helped a lot!
    – Andre Faraday
    14 hours ago










  • The yellow and blue is not a center tap, they are the ends of two windings. A center tap is continuous through the transformer and cannot be separated.
    – Harper
    9 hours ago















Thank you very much! Helped a lot!
– Andre Faraday
14 hours ago




Thank you very much! Helped a lot!
– Andre Faraday
14 hours ago












The yellow and blue is not a center tap, they are the ends of two windings. A center tap is continuous through the transformer and cannot be separated.
– Harper
9 hours ago




The yellow and blue is not a center tap, they are the ends of two windings. A center tap is continuous through the transformer and cannot be separated.
– Harper
9 hours ago












up vote
6
down vote














Firstly, I want to use a transformer that can both take 220V and 110V inputs. Can I use a center tap transformer and for 110V put the coils in series and for 220V only use one coil and leave the second open circuited?




The normal approach is to use a transformer that has two identical primary windings, each rated for 110V and half the total transformer power. You put them in parallel for 110V operation and put them in series for 220V operation. This optimizes the amount of copper required.




Secondly, I need an output of + and - 15, so do I select a transformer with a center tap secondary and wire the two identical outputs to be 180 degrees out of phase?




If you ground the center tap, you can use the other two terminals to make separate +15V and -15V supplies. The fact that they are out of phase allows you to use full-wave rectification for both supplies.




Lastly, I cannot find any transformers with these specifications.




That would be a product recommendation, which is off-topic here.






share|improve this answer




















  • Yeah, and don't attempt to half-wave rectify them unless either your load is balanced or your transformer mount is very sturdy and well dampened :)
    – rackandboneman
    8 hours ago














up vote
6
down vote














Firstly, I want to use a transformer that can both take 220V and 110V inputs. Can I use a center tap transformer and for 110V put the coils in series and for 220V only use one coil and leave the second open circuited?




The normal approach is to use a transformer that has two identical primary windings, each rated for 110V and half the total transformer power. You put them in parallel for 110V operation and put them in series for 220V operation. This optimizes the amount of copper required.




Secondly, I need an output of + and - 15, so do I select a transformer with a center tap secondary and wire the two identical outputs to be 180 degrees out of phase?




If you ground the center tap, you can use the other two terminals to make separate +15V and -15V supplies. The fact that they are out of phase allows you to use full-wave rectification for both supplies.




Lastly, I cannot find any transformers with these specifications.




That would be a product recommendation, which is off-topic here.






share|improve this answer




















  • Yeah, and don't attempt to half-wave rectify them unless either your load is balanced or your transformer mount is very sturdy and well dampened :)
    – rackandboneman
    8 hours ago












up vote
6
down vote










up vote
6
down vote










Firstly, I want to use a transformer that can both take 220V and 110V inputs. Can I use a center tap transformer and for 110V put the coils in series and for 220V only use one coil and leave the second open circuited?




The normal approach is to use a transformer that has two identical primary windings, each rated for 110V and half the total transformer power. You put them in parallel for 110V operation and put them in series for 220V operation. This optimizes the amount of copper required.




Secondly, I need an output of + and - 15, so do I select a transformer with a center tap secondary and wire the two identical outputs to be 180 degrees out of phase?




If you ground the center tap, you can use the other two terminals to make separate +15V and -15V supplies. The fact that they are out of phase allows you to use full-wave rectification for both supplies.




Lastly, I cannot find any transformers with these specifications.




That would be a product recommendation, which is off-topic here.






share|improve this answer













Firstly, I want to use a transformer that can both take 220V and 110V inputs. Can I use a center tap transformer and for 110V put the coils in series and for 220V only use one coil and leave the second open circuited?




The normal approach is to use a transformer that has two identical primary windings, each rated for 110V and half the total transformer power. You put them in parallel for 110V operation and put them in series for 220V operation. This optimizes the amount of copper required.




Secondly, I need an output of + and - 15, so do I select a transformer with a center tap secondary and wire the two identical outputs to be 180 degrees out of phase?




If you ground the center tap, you can use the other two terminals to make separate +15V and -15V supplies. The fact that they are out of phase allows you to use full-wave rectification for both supplies.




Lastly, I cannot find any transformers with these specifications.




That would be a product recommendation, which is off-topic here.







share|improve this answer












share|improve this answer



share|improve this answer










answered 16 hours ago









Dave Tweed

115k9143252




115k9143252











  • Yeah, and don't attempt to half-wave rectify them unless either your load is balanced or your transformer mount is very sturdy and well dampened :)
    – rackandboneman
    8 hours ago
















  • Yeah, and don't attempt to half-wave rectify them unless either your load is balanced or your transformer mount is very sturdy and well dampened :)
    – rackandboneman
    8 hours ago















Yeah, and don't attempt to half-wave rectify them unless either your load is balanced or your transformer mount is very sturdy and well dampened :)
– rackandboneman
8 hours ago




Yeah, and don't attempt to half-wave rectify them unless either your load is balanced or your transformer mount is very sturdy and well dampened :)
– rackandboneman
8 hours ago










Andre Faraday is a new contributor. Be nice, and check out our Code of Conduct.









 

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