Dear diy friends,
I want to buy a 80va toroidal transformer, but the problem is, it has 240volts input primary and our local voltage is 220volts. Will it be ok? what is the disadvantage of this setup?
thanks.
I want to buy a 80va toroidal transformer, but the problem is, it has 240volts input primary and our local voltage is 220volts. Will it be ok? what is the disadvantage of this setup?
thanks.
Indeed! 
The disadvantage is possibly a bit heavier transformer than necessary but nowadys much electric gear (in Europe at least) is designed for 220-240 VAC.
The disadvantage is possibly a bit heavier transformer than necessary but nowadys much electric gear (in Europe at least) is designed for 220-240 VAC.
Shouldn't be a problem at all.
The only disadvantage is that the maximum power you can get out of it will be very slightly less. Not enough to worry about, anyway.
The only disadvantage is that the maximum power you can get out of it will be very slightly less. Not enough to worry about, anyway.
Thank a lot ,
The transformer will be feeding a regulator for a Pass class A preamp, So the power loss is practically none issue...I guess.
Thanks.
The transformer will be feeding a regulator for a Pass class A preamp, So the power loss is practically none issue...I guess.
Thanks.
It should be fine.
Incoming ac supply may fluctuate sometime. To avoid it, you may need a regulated supply.
The ratio of your trans difference for 240 and 220. Let say, secondary is 12v then
1)12/240= 0.05 ;
2)12/220 = 0.0545 ;
If the supply for the trans no.2 is 240vac then the secondary will be 240 x 0.0545 = 13v
Incoming ac supply may fluctuate sometime. To avoid it, you may need a regulated supply.
The ratio of your trans difference for 240 and 220. Let say, secondary is 12v then
1)12/240= 0.05 ;
2)12/220 = 0.0545 ;
If the supply for the trans no.2 is 240vac then the secondary will be 240 x 0.0545 = 13v
My regulator needs 18V AC to produce a 15V DC , Do you think there is still enough headroom for the regulator to regulate, When you factor the slight voltage drop, Due to the primary mismatch? If I buy a transfo. with 240V pri./ 18-0-18 secondary plugged into a 220 outlet?
Thanks.
Thanks.
At 220v in will give 16.5 - 0 - 16.5, that might just save your regulator, rectified the 16.5vAC will give 23V peak instead of 25.5V a saving of 2.5watts dissapation per amp drawn from the regulator.
Bit simplistic and others will do the full maths with transformer regulation and diode drop taken into account - It will do 🙂
You have measured your AC line voltage I take it? As the 220V is nominal in europe, and can vary quite a bit - also depends on how near the substation you are and how heavy are the other loads on the substation are. Carefull measuring it though - it can bite
Bit simplistic and others will do the full maths with transformer regulation and diode drop taken into account - It will do 🙂
You have measured your AC line voltage I take it? As the 220V is nominal in europe, and can vary quite a bit - also depends on how near the substation you are and how heavy are the other loads on the substation are. Carefull measuring it though - it can bite
Worst case is likely be to approximately
(18*(220/240)*0.9*0.9*1.4)-2 = 16.7V DC so it may not always be able to provide 18V DC for the regulator input.
If the transformer is only lightly loaded then the voltage will likely be somewhat higher.
(18*(220/240)*0.9*0.9*1.4)-2 = 16.7V DC so it may not always be able to provide 18V DC for the regulator input.
If the transformer is only lightly loaded then the voltage will likely be somewhat higher.
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