| Searching for toroid, 2x70V seccondary... - Click HERE for Original Thread |
| CJ900RR |
I need a toroid with primary winding 220V and seccondary winding of 2x70V, to reach 100V DC. VA-rating should be >800VA. Any ideas where to look?
The closest I have found is 65V and 110V, nothing inbetween.
Alternative I could need some guidance how to reduce voltage from 155V DC to 100V DC using passive components or step-down regulators.
Best regards, Calle.... |
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| paulb |
| You could get a custom one. Why not just use the 2x65V? |
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| AndrewT |
Hi,
have you considered adding extra turns to generate the extra 5Vac in each winding?
The wire in a 800VA 65Vac will be sized to pass 6.15Aac continuously.
If you add extra turns using the same diameter wire then you get 70Vac @ 6.15Aac, well not quite, becasue that would imply a higher VA of 861VA. It would be reasonable to assume that the modified winding could safely achieve a VA rating about half way in between say about 830VA.
It's relatively easy to remove the outer insulation and add the couple of dozen turns required. Then carefully rewrap the insulation.
BTW,
what is the mains voltage specification for your chosen transformers? are they really 220Vac or 230Vac?
What is your normal mains supply voltage? How much does it vary hour to hour or season to season? |
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| CJ900RR |
| quote: | Originally posted by paulb
You could get a custom one. Why not just use the 2x65V? |
Yes there is allways custom ones, but my guess is that it would be even more expensive....
| quote: | Originally posted by AndrewT
Hi,
have you considered adding extra turns to generate the extra 5Vac in each winding?
The wire in a 800VA 65Vac will be sized to pass 6.15Aac continuously.
If you add extra turns using the same diameter wire then you get 70Vac @ 6.15Aac, well not quite, becasue that would imply a higher VA of 861VA. It would be reasonable to assume that the modified winding could safely achieve a VA rating about half way in between say about 830VA.
It's relatively easy to remove the outer insulation and add the couple of dozen turns required. Then carefully rewrap the insulation.
BTW,
what is the mains voltage specification for your chosen transformers? are they really 220Vac or 230Vac?
What is your normal mains supply voltage? How much does it vary hour to hour or season to season? |
It could be a solution to modify a excisting one. But it would be more easy to buya premade one :)
The mains in Sweden is nowdays 230Vac but I, and allmost everyone else still say 220Vac from old habbit. The voltage usually stays near 230Vac with a +- of about 5Vac. |
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| pinkmouse |
| I'd go with the 65-0-65. I very much doubt that you'll notice the difference from 70-0-70. |
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| cliff |
| You could use two 25-0-35 torroids stacked. These are readily available. |
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| K-amps |
| Antek on ebay sells 67-0-67 but 110mains... I think they may have dual prims, in whch case hook em in series... |
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| K-amps |
| The 1.5kVa will mantain 70 volts at 500 watts... not too shabby. |
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| K-amps |
| John is very helpful. I bought mine via ebay, no issues. |
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| y8s |
| quote: | Originally posted by CJ900RR
Many thanks to you all. http://www.toroid-transformer.com/ have the perfect ones. Good priceing to! Has anyone any experience buying from them? Thanks... |
Just picked up a pair of 3222 transformers for some 41hz tripath amps and was pretty satisfied with the delivery time and pricing.
just watch out for shipping costs. those 68x2s are the size of my last birthday cake! |
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