The simplistic Salas low voltage shunt regulator

[Kazuo Ozawa]

Great. Zobel is 'not' optimized, or is 'now' optimized?

P.S. Is there a Z Foil resistor in the picture between trimmer and a BJTs pair?

Hi, Salas.
1)NOT optimized. Next step I will try. Or will anyone try?
2)Yes.

Best regard

 

[Salas]

Excellent, thanks,
Forgot 1 more: Total CCS should be equal to at least 150mA + load current?

The hotter the better but troublesome for sinking and for hitting 9610's limit eventually, so yes 150mA extra is logically good. Nothing stops you to run say 250mA extra if its a 9V reg for a 50mA load so the heat is still manageable of course.

 

[Phisci]

Why does Kazuo get better results with a STP55NF06L? What changes in going from 640? What alternatives would you suggest to STP55NF06L if not available?

 

[Salas]

Hi, Salas.
1)NOT optimized. Next step I will try. Or will anyone try?
2)Yes.

Best regard

Now I see, you mean you want to still investigate about the Zobel and sonics regarding the new ST MOSFET. Now values come from the high capacitance Renesas we tried to get better before.

Since you got the nice 200 MHz Tek scope just watch that the now firm stability is not compromised during tuning it.

 

[Salas]

Why does Kazuo get better results with a STP55NF06L? What changes in going from 640? What alternatives would you suggest to STP55NF06L if not available?

Kazuo is trying below 5V and he had to find an optimal low Vgs threshold Mosfet. He got a little unlucky with the first one, a Renesas. 640 is fine for the normal reg.

 

[Salas]

P.S. I will have to wrap up the REFLEKTOR in a short pdf guide soon I guess, since enough seem to try it by now.

 

[Phisci]

Sorry for the ignorance, but how does Iref relate to Total I or Load I or Shunt I in Vout=(Iref*R6)+(2Vbe+VfD1) and as importantly, how does that all relate to Vgs for IRF640?

And also, does your guide of Min(Vo-Vi)>=5V still hold?

 

[Salas]

As the 640 biases open its Vgs is about 4V. That one is a steady parameter in the circuit. It creates 4mA current through the 1K left side load resistor. This current is auto matched to the right side of the mirror and creates the reference voltage for the system by I/V transformation on the trimmer, adding the LED drop and two transistors drop of that side also.

Yes, the 5V minimum drop across the regulator recommendation has never changed.

 

[Phisci]

That's great Salas! I may actually be starting to understand some of the ways in which the reflektor works through your kind efforts!

Vout=(Iref*R6)+(2Vbe+VfD1), where Iref = Vgs/(left side load reflektor). For IRF640, Vgs= 4V
R6 is the pot;
Vbe is for 2N4403
VFD1 is for diode in mirror

1. Total CCS current is (2N4403)Vbe/R1 = load current plus shunt current = load current plus ca 150mA as a guide
2. Absolute value of Min (Vout-Vin) >=5V
3. The dissipation on 9610 mosfet is (Vin-Vout)*(CCS current)
4. The dissipation on 640 mosfet is (Vout)*(CCS current-Load current)
5. Adjusting the Reflektor for different optimal currents, the best way would be to change R1

 

[Salas]

In very simple circuits the loops and sources are not relegated to specialized sub circuits that are obvious in the drawings, and it can be puzzling.

 

[Kazuo Ozawa]

Now I see, you mean you want to still investigate about the Zobel and sonics regarding the new ST MOSFET. Now values come from the high capacitance Renesas we tried to get better before.

Since you got the nice 200 MHz Tek scope just watch that the now firm stability is not compromised during tuning it.

OK, you always encourage me forward. will try and report later.

Best regard

 

[Salas]

1R 0.47u is quite different to listen to for instance. If stable on the scope as the other, you can see where it goes, if there is something to gain or lose in lower values or to stay where it was. Like a recognition shot.

 

[Salas]

I will get some STP55NF06 regular Vgs now that are everywhere to shop. For higher than 5V because still low pF and good transconductance so to evaluate for my REFLEKTOR wrap up. Higher voltage range with KSA1381 9610/20 640, medium with 2N4403 or BC327 STP55NF06 or FQP50N06 9620/10, Medium/Low with STP55NF06L or FQP50N06L.

 

[Bksabath]

Hi Sallas I look forward to try the new Reflector I am planning on a 35 or there about Simplistic

By time I get a proper build of it to use as reference.
It has been a long time since I was going to do it and I have 1000 2N4403 just sitting there.

 

[50AE]

Because my DAC runs on battery, I decided to increase the resistors value a bit on the regulators, to decrease the current. The default ones were cheap wirewounds. I put metal film ones, Tesla TR16* . I didn't think of anything about sound quality, I was just thinking about how great it will be that my battery will last more.

I started playing music and WOW!! Can't explain how much more detail appeared, I was amazed. I underestimated resistors and DAC PSUs untill now. Because of throwing away two wirewounds, I now rediscover my music again!

 

[Salas]

Which type of regulators exactly? Some are raving about thick film ones in bib and dcb1 by the way.

 

[50AE]

5V and 3,3V v 1.1

 

[Salas]

Some others had also told the setting resistor can be picked up there in the builds thread, yes. When I had changed MOX to Caddock thick film in double mono 1.1 in a phono I had done other stuff in the main circuits too, so I can't attest even an uncontrolled delayed A/B opinion unfortunately. Nice that you got better sound, congrats.

 

[Phisci]

Hi Salas, is there an equivalent resistor to the one changed in v1.1 in the reflektor?

 

[Salas]

Yes, R1, but its already metal film since its not high power. Dissipation on it is 0.65V times CCS current. 1W will do in most HOT ROD cases even for 0.5A.