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OLD THREAD DAC End by Andrea Ciuffoli

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Yunick

Member
Joined 2006
Everything is finished, but I'm still waiting for a new CS8414.
I think it died during my attempts to solder it to the converter PCB.

But I have measured everthing twice to make sure everything is in working order before the new CS part gets here. And it seems I have some work to do on the Salas psu..
 
A

Agi

Member
Joined 2008
adamus said:
same for me if you read back, infact exactly the same on the 5+v dig.

At 'max' the salas board is not regulating, the final mosfet isnt doing anything. its not ideal, but increase parallel another 27r with the rset resistors which will increase the 5.19 to 5.3 ish... then back off a little to ensure regulation. The tl431 doesnt need much headroom unless my scope is lying.

Salas, i had a play with the dig line. when the shunt reg 'maxes out' the vgs goes to zero on the final mosfet. back off a little and it comes up to 4v or there abouts. any ideas?
Click to expand...

I noticed that as the end mosfet doesn't even get warm. Stays dead cold.
However the -ve 5 analog one does get warm...

So where do i need to put a 27 resistor?
Parallel to r14 and r2?
 
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Agi

Member
Joined 2008
R13 and R1 then?

Ok after some looking into I have 0.02v across the drain and source of the second fet in the digi 5v.
I get 3.7v ish across the other "seconds". I.E number 2 of 5v analog and -5v analog.

After more investigation as soon as i drop +5v digi to 5.15 or less i get 3.6ish across the second fet...
Am i better running it like this?
 
Last edited:
quanghao

quanghao

Member
Joined 2009
quanghao.com/
Yunick said:
I tried parallel a 10r resistor with the R13 and could adjust up to 5.50V without Q16 Vgs dropping below 3.80V.. Great! But now Q13 got really hot instead :/ Guess I have to change the 10r to something with higher r.. Or add a bigger sink on Q13..

Thanks guys for sharing.
Click to expand...

you can use 2 x 33R parallel. So need heansick for Q13, it is hotter!
 
quanghao

quanghao

Member
Joined 2009
quanghao.com/

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