The simplistic Salas low voltage shunt regulator

[Salas]

35 το 40ish will be good. You don't wanna go far up to save dissipation on the CCS. It will be running 250mA times the voltage across the reg.

 

[tinitus]

 

[Salas]

How much current your application asks for?

 

[tinitus]

hmm, not sure
maybe 2x 3 gain stages of j310 (simple boz variant)
or just 3 stages
I have trafo with dual secondary, could make one reg for each channel
I think each jfet runs at about 5ma or so, not much
what is that ? 1watt ?

 

[spartan]

shunt reg for simplistic riaa

Salas,
For the regulator on the attached pdf, aren;t the values for the VDC and VAC mixed up? It's not clear to me what you mean by "The input voltage of the shunt is 38 or 48 V DC, so a 28 or 36 V AC transformer is needed".
Can you please clarify what should be the input DC voltage to the regulator if I'm using the 28V (MM) operating circuit? Is it 36, 38, or 48V? Can you also confirm where I should go in with that voltage in the regulator?
I don't know what "force wire" and "sense" refer to either..

 

[Salas]

28VAC x1.35=38VDC. Don't expect x1.414 with real components. 10V drop over the regulator is a recommended number for it to work fine including some mains tolerance even.
Nothing looks mixed up.

 

[Salas]

Sense and force are 4 wire Kelvin connections.

 

[spartan]

I guess I was confused by the operating voltage of the phono stage (28 or 38) and the transformers needed for the reg. Sorry about that and thanks again.

 

[didiet78]

I have got double layer with on board rectification and filtering. Maybe you can follow some ideas from it though. If you will have your raw DC part on a different board add a decoupling capacitor across the reg's board input.

New reflektor Circuit using bipolar or Just use Bipolar Library for Mosfet? If later, it got wrong pinout. Drain M1 connect to Drain M2.

Didiet

 

[alibear]

Hi all, is there a formula to calculate the heat sink size to accomodate both IRFP9240 transistors when using a version 1 circuit.
Thanks for your help
Alan

 

[Salas]

New reflektor Circuit using bipolar or Just use Bipolar Library for Mosfet? If later, it got wrong pinout. Drain M1 connect to Drain M2.

Didiet

Bipolar library was. MOSFETS used are GDS for pins as we face them from left to right. I will look into it.

 

[Salas]

Hi all, is there a formula to calculate the heat sink size to accomodate both IRFP9240 transistors when using a version 1 circuit.
Thanks for your help
Alan

You got to calculate dissipation for each one, then the rise above ambient for total dissipation on a given sink, then add the thermal resistances case to junction and about 1W/C case to sink, looking to stay under 100C for junctions. 70-85C for junctions would be very long time safe.

 

[tinitus]

Salas, I have question

looking at ordering parts for the Reflektor reg

is voltage too high to use 2sk170 instead of 2sk117 ?

 

[Salas]

The JFET is going to have about 35V across in your case. K170 has 40V max. Make R4 120R if it will be a BL range to save the JFET some dissipation. I prefer the K117 for it being less capacitive and 50V rated. But both can do, except than in the odd input over-voltage of course.

 

[tinitus]

will see if I can get some k117
or use heatsink with the k170
ok, thanks

edit, I have found and bought a few 2sk117, if all goes well

 

[Furax]

Hi there ! I am a little bit lost in the ...558 page of this thread ! I am looking for 2 power supply: 5V/ 250mA and 5V / 100mA for my DAC (a TOTALDAC). Welle, do you have a link to a page for a good incarnation of your design in this range of tension and current?

 

[Salas]

Look in SSLV1.1 builds thread for something plausible with pcb etc. Here is an ongoing ideas and tests and questions thread with enough yrs of stories.

 

[E30NA]

Is it possible to build a 12v 2a version of this PSU?

 

[AndrewT]

I don't know what you have in mind, but those numbers will impose certain dissipations in the Salas Style Shunt Regulator.
First, the 12V output will require a nominal 19Vdc including quite a bit of ripple.
Second, this in turn will result in a range of input voltage of 17Vdc (absolute minimum) to 19Vdc.
Third, 2A of output will likely require at least 2.03A of input.
Fourth, 19V * 2.03A gives a maximum dissipation for the whole regulator of 38.6W.
Fifth, you have to get rid of that heat using heatsinks.

I would not use a Shunt regulator for this duty, I recommend a series regulator.

 

[E30NA]

Thanks for the quick reply.

Ok, i can see that there are to many compromises by using this PSU then. I am looking around for a better PSU for my DAC Magic Plus, and just gathering information and ideas. DDAC have recomended me to try his PSU Construction, and i am leaning to that sollution. But i want to keep my options open before i make my decission on what PSU to choose.