70V 5A symmetrical PSU HELP :D

[firefart_1st]

I'm designing an enormous power supply for a school project.

it is rated at about 70V 5A symmetrical.
and my problem is very simple...
the circuit driving the power transistors does not let me go further than 15V or so.
the voltage reference and symmetrical adjustment are feed on 15V.
I don't know what to do now. I'm posting here for Heeeeelllllpppp
any adjustments to the circuitry are totally welcome!
i did not yet calculated everything.

the circuit to correct the problem should be inserted in the little empty square. feed on the positive and negative rail's that can see 90V when not on load.

link-> http://userphotos.hi5.com/0008/426/353/ca0NZ7426353-02.jpg

sorry for the low quality... I don't know were to load that image.

the psu is simply an voltage reference circuit. and symmetrical adjust (according to output) circuit. and the power transistors.

I will be waiting for an reply on this subject...

 

[firefart_1st]

has no one said anything yet

i got the schematics uploaded right!!

here is the link
::

http://item.slide.com/r/1/122/i/vG1J98KM6j-CzT_ZlVeLXcjsQoJbY3JY/


and it has a correction already.

 

[MJL21193]

Change your 50-0-50 supply rectification to single bridge such as shown below.

 

[MJL21193]

BTW, 70v,5A isn't enormous. I have +/-70V, 11 amp (800va) single bridge supply.
Keep it simple.

 

[firefart_1st]

the second bridge is just in parallel. is it for better power dissipation.

still ir does not work very well... and I'm designing it.