Audio Mixing Desk

[Diarmuid]

Hi, I am new here, as I came across this site searching for help with my first HUGE project.

[Staigen]

Hi Diarmuid, welcome to this foum, nice to have you here ;D

Here you get at least some answers to your questions! :)

for the transformer, would these be ok, in specific 88-3419 and 88-3420, for the transformers in figure one, of the PSU section?

The tranny(short for transformer) T1 should, according to the specs, be a 150 VA type, and if it is going to put out 4 Amps, that's a little bit on the low side, i belive!
The tranny T2 should, also according to the specs, be a 20 VA type, yours are only rated at 6 VA!

Also, in the PSU section, what are DB1 and DB2

This is Diode Bridge, rectifier bridges, the DB1 is a 25 Amp type and DB2 is a 5 Amp type

I come back later with some more about this PSU later, i have to go

//Staigen

[Staigen]

Hi, i'm back

If you look closely at rectifier 2 and its surrounding parts, you see that the CT of tranny 2 is not needed, no load is connected to it. By removing the CT connection and one of the filter caps you get lower ripple. The remaining filter cap must have a higher voltage rating thou, 80V or 100V is enough!

Then it is the regulators! If you have a short or overload they are going to blow, there is no current limiting to talk about! I havent looked at the rest of the project!

//Staigen

[Diarmuid]

Thank you so much for all your help so far.
The only transformer I can find that is above 150VA, is a 200VA one, the site mentioned that it would be possible to use a higher transformer, however it mentioned that the fuses and Caps would need raising to a higher limit.

[Staigen]

Hi Diarmuid

A 40V CT @ 200VA for T1 is just fine, no need to rise the caps for that, but 10,000 uF caps will make the ripple less, always good, 40 Volts caps is fine here.

For T2 you only need a 20 VA tranny, 50 Volt without CT is just fine here, and a cap of 4700 uF @ 80V or 100V is just fine here.

The primary fuse(F1) maybee need to be increased somewhat, test! And, not more than 1.5 Amps, i think.

//Staigen