#26 pre amp

[merlin el mago]

Try to add resistances and inductances of wires into your SIM, variable current drawn, and you will see why ground sign have to be drawn near C3 instead of near C1.

I always read all people said to connect the ground to 1st cap psu😕

 

[merlin el mago]

Felipe, that's not my design. Either way 12mvpp ripple is not bad at all! Are you planning to use a shunt regulator?
Ale

I'm sorry Ale the post was for Andy. Yes, Salas hig voltage shunt regulator version 2🙂
Felipe

 

[merlin el mago]

Felipe, can I do some comments?

Such a low transformer DCR not optimal for (mesh) AZ1. It would be better 100-200R DCR.
IMHO C1 low, thus output voltage also low. There are no high charging current (AZ1 unable to do so) therefore increase C1 up to 1-5uF. If output ripple bothering you, increase C3.

ps. PSUD a little cheating, output voltage about 220V, not 230.

Ps2. Attachment is my working #26 preamp (common raw PSU- each side: SSHV2- cascode CCS loaded 26 -TVC) raw HT supply.

Of course you are welcome, you are right because one time for other project I use AZ1 with other transformer with secondary DCR 83,2 ohms and was to add one resistor in series with the phase of 78 ohms or AZ1 not optimal.

Thanks for support and advices🙂

 

[palmas]

Ale I have simulated your PSU, simulator saids have more ripple, or I'm misunderstanding something, see attached image.

In simulation you have 10H 10Ohm chokes for 30mA
More realistic would be 100 to 300Ohm choke. That can make some difference on the outcome

 

[merlin el mago]

In place to use two 125VAC in series what about to use as an isolation transformer to get 230VAC, due to the fact that I don't need so hign voltage can get a better psu?

 

[merlin el mago]

In simulation you have 10H 10Ohm chokes for 30mA
More realistic would be 100 to 300Ohm choke. That can make some difference on the outcome

Thanks for advice, could I add in series resistor 290R? could you elaborate so I can learn? psud2 don't show any difference of ripple.

 

[palmas]

Thanks for advice, could you elaborate so I can learn.

10H chokes have thousands of spirasl in a iron (typically) core, so you cannot use big seccion wire, or it won't fit, or it will be enourmous and very expensive.
So you use thin wire (as requested by the 30mA), so wire resistance will be a lot higher than 10Ohm. Fro experience (I build them myself) for a 10H 200mA choke resistance will be about 100Ohm and for a 10H 100mA typically about 300Ohm. For 30mA could be more.
If you make that change on the simulator you will see that output voltage and ripple are a little different.

By the way, 0,1Ohm on caps is also too low if you're using electrolitic.

Cheers

 

[palmas]

😱
did you measure inductance with 100mA?

 

[merlin el mago]

10H chokes have thousands of spirasl in a iron (typically) core, so you cannot use big seccion wire, or it won't fit, or it will be enourmous and very expensive.
So you use thin wire (as requested by the 30mA), so wire resistance will be a lot higher than 10Ohm. Fro experience (I build them myself) for a 10H 200mA choke resistance will be about 100Ohm and for a 10H 100mA typically about 300Ohm. For 30mA could be more.
If you make that change on the simulator you will see that output voltage and ripple are a little different.

By the way, 0,1Ohm on caps is also too low if you're using electrolitic.

Cheers

Thanks for advices, I use Bartolucci chokes are rated 10H 100mA 10 ohms, attached pic.

I'm using mkp in oil ASC X386S, attached pic.

Cheers
Felipe

P.S. How can measure lytics impedance?

 

[palmas]

I need to buy these bartolucci chokes and reverse engineer them!

About the caps it is easier to rely on manufacturer specs and calculate connections resistance. But there is not a significant difference from 0.1 to 1Ohm on the cap

 

[euro21]

😱
did you measure inductance with 100mA?

Why not? 🙂

 

[massimo]

I always read all people said to connect the ground to 1st cap psu😕

No Felipe, Wavebourn is absolutely correct. If you use R or L, the new ground point becomes the lastest Cap minus pin

 

[merlin el mago]

I was confused, thanks Massimo, how about the power tx: use isolated two tx 230:125/125:230VAC or two in series for 250VAC?

 

[Wavebourn]

I always read all people said to connect the ground to 1st cap psu😕

Now you know better than "All people that said" 😉

 

[merlin el mago]

Hey guys, coming back to my psu, what do you think is better:

-Isolated tx 230VAC
-Series tx 250VAC

Thanks for comments.

 

[merlin el mago]

Now you know better than "All people that said" 😉

I like to learn🙂

 

[merlin el mago]

More or less the ripple is the same 11-12mV so it seems to have more advantatge using two configurated as one isolation tx, attached psud2 pics, what do you think?

 

[merlin el mago]

Using two txs as isolation wich gnd have I to connect to mains: the 2nd tx of the 1st tx & left the 1st floating?

 

[merlin el mago]

Have I to connect the mains tx ground as per schematic?

 

[rclourenco]

FINISHED!

Last photos of my implementation: The Supply Chassis!

Final result: Incredible clear #D presentation, dead quite with virtual zero noise on the speakers (even with your ear deep inside the mid/woofers).

I am very happy, the final result is really impressive.
Thanks to all (Thomas, Ale, Kevin and Rod) for your strong help and support.