AC/DC advice

[Holger]

I need +30V and -10V for an 1176. My transformer (nomial 2x 25V) supplies some 29V AC, but I only get out some +25V max. on the DC side. Can someone give me a hint what to do? Or do I really need a nominal 2x 30V transformer?

[Joe Malone]

I need +30V and -10V for an 1176. My transformer (nomial 2x 25V) supplies some 29V AC, but I only get out some +25V max. on the DC side. Can someone give me a hint what to do? Or do I really need a nominal 2x 30V transformer?

No the 2 x 25vac transformer should give you +/-35vdc unreg for the normal +V and -V regs on the AC/DC so should adjust up just fine. Do you have the phasing of the 2 x 25vac windings correct. And the centre tap connected to 0v and the other to winding ends to a AC in each?

Or are you trying to use the +48v rail for the +30v without fitting the Doubler wire strap? I would only use the +V and not the 48v rail for the +30V unless you were using a 2 x 15vac transformer as then the 48v rail would be fine as it would not be wasting to much heat.