-1

Should i replace a 13.5-0-13.5 2.5A transformer (seems to be a custom made ) found in a chinese home theater with a 12-0-12 3A or 15-0-15 3A .Which would be better ?.Any suggestion would be great. Thanks

John
  • 13
  • 3

2 Answers2

1

schematic

simulate this circuit – Schematic created using CircuitLab

Figure 1. Adding back-to-back diodes in the 15 V output lines will reduce the voltage on each line by 1.4 V.

You need to select diodes capable of 3 A. Be aware that at low output currents the voltage will rise as there will be lower forward voltage drop across the diodes.

Transistor
  • 168,990
  • 12
  • 186
  • 385
0

Nobody can tell you for sure, because we do not know what is behind the transformer.

I would give a try to 12-0-12/3A. Probably there is enough tolerance to make it work, but you cannot be sure until you try it. There is good chance it would work fine.

15-0-15 is a little risky, because most electronics do not handle well over-voltage conditions. But it may work fine, also.

None option cannot be guarantied to work, but 12-0-12/3A is the safer choice here. I would say it have better chance of working properly.

Darko
  • 879
  • 6
  • 12
  • 1
    Depending on what is behind the transformer the opposite might be the case: the 12v causes undervolt with potential for damage and the 15 will just stress the regulator a bit more. Any scenario is possible, thus recommending any is not possible – PlasmaHH Oct 12 '17 at 10:39
  • I have written that there is higher chance that 12 is safer. There is small chance that lower voltage could damage something, although such circuits exists ofc. – Darko Oct 12 '17 at 14:02
  • I would expect that all sensitive electronics are behind some voltage regulation (to some smaller voltage). I guess this +-13.5V is used for output stage transistors (audio). In that case, lover voltage would just give smaller maximum audio power. – Darko Oct 12 '17 at 14:04
  • I find nowhere an indication that this is about audio, and the DC rails would be 19Vish anyways. Even if this was audio, it could be feeding a D class FET amplifier which could fry with too low voltage. In either direction there is many possibilities how something can go wrong, without knowing what comes after the transformer, nothing is safe to assume it might work. – PlasmaHH Oct 12 '17 at 14:39