Need help with a psu

[flaheu]

I've got a 25V-0-25V Transformer and also a psu board which is the one used for the Calrec (+/- 15V "generic board" ) designed by Jacob.

Question: Is the TX too "hot" for the 7815 and 7915 used on this board, based upon my calculations (which I'm not sure of) the voltage going into the regulators seem to be close to their max input voltage limit.

Shoul I worry ? Should I drop the voltage before the regulators ? If yes how.

This may sound stupid, but I have to keep this transformer as I have to make 48V regulated 1A with it also.

Thanks in advance.

 

[Samuel Groner]

I don't think there is a convenient way of getting both +/-15 V and 48 V out of just two secondary windings, particularly at the high current you're asking for the 48 V--unless the 48 V could actually be a +/-24 V..?

Samuel

 

[rodabod]

How about a voltage doubler for the 48V,and some decent heat-sinking if the circuit decides to sip a reasonable amount of current?

 

[Samuel Groner]

At 1 A a voltage doubler seems to be bound to be rather inefficient, but who knows.

Samuel

 

[rodabod]

At 1 A a voltage doubler seems to be bound to be rather inefficient, but who knows.

I missed the 1 amp bit - I assumed it was for phantom power. Still might be worth a shot though if you refuse to use a different transformer.

 

[amorris@home]

1A? @ 14ma per mic, thats 71 mics.

 

[Samuel Groner]

Nobody said it is for phantom power.

Samuel

 

[rodabod]

Maybe some telecomms equipment? 

 

[maxwall]

Have you checked with JLM audio , I know he sells PSU boards you can stuff at a reasonable price.

 

[flaheu]

I have to clarify a few points.
The 48V is needed for 4 JLM BA preamps, but 1A is maybe overrated, I think 500mA is enough.
Right now I have a crapy 48V SPSU (digital telephone inline SPSU), I want to get rid of it.
I've got no space for a second TX, that's why I would like to replace my current TX (15v-0-15v) which feeds a 7815/7915 board by a 25v-0-25v TX.
This 25v-0-25v would also feed the +/- 15v regulation board (which is used for 4 led peak meters) and a 783 tiny board for 48 v regulation to replace this crapy switching psu.
Don't know if clear enough, It's mostly a question of space.

I know the JLM stuff, I used a lot of their stuff, it's good quality, but the delivery time would be too long.
I need to find a solution quickly, sessions are booked.

Thanks