what tx needed

paul.42 · 23rd October 2011, 10:35 AM

hi all,how do you work out what tx is needed if it is +/- 50v after retifacation.

AndrewT · 23rd October 2011, 10:44 AM

35Vac gives ~ 50Vdc, 35+35Vac gives ~ +-50Vdc.
Check through a few posts. You will find many estimating methods and a few that get much closer to reality. All involve the use of SQRT(2).

You need to know the rated input voltage as well as the rated output voltage of your proposed transformer. You also need the VA or current rating and the regulation figure of the transformer.
Finally you need the "normal" voltage available at your home. This "normal" varies from minute to minute and hour to hour, but should always be between the tolerance limits specified by your electricity supplier. Except when there is a mains failure where zero volts becomes available or "brown outs" when the available voltage falls below the lower tolerance limit.
As listeners we would not design for continued maximum sound quality during "brown outs". But we would design for "no damage" in event of mains failure and repeated attempts at restarts.

mickeymoose · 23rd October 2011, 02:43 PM

Attached a handy chart. E

paul.42 · 24th October 2011, 08:29 AM

thanks guys.

23rd October 2011, 10:35 AM	#1
paul.42 diyAudio Member Join Date: Jul 2007	what tx needed hi all,how do you work out what tx is needed if it is +/- 50v after retifacation.

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23rd October 2011, 10:44 AM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	35Vac gives ~ 50Vdc, 35+35Vac gives ~ +-50Vdc. Check through a few posts. You will find many estimating methods and a few that get much closer to reality. All involve the use of SQRT(2). You need to know the rated input voltage as well as the rated output voltage of your proposed transformer. You also need the VA or current rating and the regulation figure of the transformer. Finally you need the "normal" voltage available at your home. This "normal" varies from minute to minute and hour to hour, but should always be between the tolerance limits specified by your electricity supplier. Except when there is a mains failure where zero volts becomes available or "brown outs" when the available voltage falls below the lower tolerance limit. As listeners we would not design for continued maximum sound quality during "brown outs". But we would design for "no damage" in event of mains failure and repeated attempts at restarts.

24th October 2011, 08:29 AM	#4
paul.42 diyAudio Member Join Date: Jul 2007	thanks guys.