Preamp/Phantom/Relay PSU - Some help please....

Hi,
please take a look at my PSU schematic. What do you think?



The first 48 V is fpr Phantom, the 2. 24 V is for my Neumann preamps and the 3. 24 V is for the relays i use.

Can I do it like that? Shuld I add a 51 V Zener diode at the 48V circuit to make shure not more then 51V goes to the microphones if the 7924 goes wrong?

Give me some tips please...

Thanks
Leslie....

You could do that, but there's no reason to make it that complicated.

Use 7824 regulators for 24V.

Use a LM317 for 48V. Or a transistor/zener like in the G9. Just don't short the output.

and btw, 1000uF is a bit too small for primary reservoir caps. Depending on your current, use 4700-10.000 uF. For the phantom, 1000uF will do fine.

Jakob E.

Leslie
I am just a newbie here - but I have a few questions if you don;t mind...
But how do you get 48v from a 7824 regulator - and what does that 7924 do?
Is it to do with reference voltages?

[quote author="gyraf"]You could do that, but there's no reason to make it that complicated.

Use 7824 regulators for 24V.

Use a LM317 for 48V. Or a transistor/zener like in the G9. Just don't short the output.

and btw, 1000uF is a bit too small for primary reservoir caps. Depending on your current, use 4700-10.000 uF. For the phantom, 1000uF will do fine.

Jakob E.[/quote]

Thanks Jakob! Ok the cap was a fault in the circuit. I just copied it from the Phantom section. You are right....

Yes I could do it with a LM317, but i want 3 currents they do not influence each other, coause the neuman modules have a single ended PSU but they use 5534. So i wanted to have also a "regulatet" ground (sorry for my bad english...)...
I will think about it one more time. perhaps you are right.... :grin:

[quote author="uk03878"]Leslie
I am just a newbie here - but I have a few questions if you don;t mind...
But how do you get 48v from a 7824 regulator - and what does that 7924 do?
Is it to do with reference voltages?[/quote]

The 7924 is a negative regulator. When you make a +24 and a -24 Voltage and put the -24 to ground you have 48V between ground and the "hot" pin....

Just a suggestion... possibly add some diode protection on those regulators?

[quote author="Greg"]Just a suggestion... possibly add some diode protection on those regulators?[/quote]

Shure. I only wanted to show the idea. Its not all in. Also the Caps have the wrong values.... Wanted to add a 51V Z Diode for protection in the Phantompower stage and put some 150 OHM Resistors in Front of the Bridge, so the 150 Ohm resistor works as a Current restriction for the Z Diode....