SSLV1.1 builds & fairy tales

[vgeorge]

Hi Salas

Starting to build the SSLV1.1 but my boards have 4 leds for biasing the ccs mosfet. The build guide only has reference to three.

Why the fourth led ?

Ricardo,
if you want to use higher current, you cant use a higher value resistor with 4 leds. That' s why they use 4 leds in the last pcb. You can always short the forth led and use 3.

 

[RCruz]

Hi vgeorge, I usually use a lower value resistor to set higher current.

Using four diodes with a higher value resistor is new to me... but I found it:
(3xVf LED)-VgsQ101=VdR101. ICCS=VdR101/R101. Example: 3x2.1V LED and a Q101(201,301) MOSFET
with 4.3V Vgs will create 2V drop across a 10 Ohm R101. ICCS=2V/10R=200mA.

So 4 leds will create a 4V drop over R101... if I use R101=15 I get ICCS = 267mA

Perfect

 

[vgeorge]

4 leds come handy if you want more than 500 mA.
Your calculations seem correct and the end result will depend on actual Vgs and leds Vref values.
If you compare with your 1.2 builds, I will be very interested for your opinion.

 

[Salas]

Hi Salas

Starting to build the SSLV1.1 but my boards have 4 leds for biasing the ccs mosfet. The build guide only has reference to three.

Why the fourth led ?

 

[RCruz]

In reality the BiB spreadsheet allready has all the calculations needed... must be more carefull in the future 🙂

 

[Salas]

You should do the VGS curves of 9530 by eye because the curve embedded in the calc is for 9610. They are Interchangeable on board, but 9610 is the fastest one for open treble while 9530 being no real dork but not as good is the tougher one for special purposes like delivering 1A and beyond to things like WiFi music centre appliances.

 

[Salas]

Read http://www.diyaudio.com/forums/power-supplies/192625-sslv1-1-builds-fairytales-203.html#post3274708 for an IRF9530 example and its curves annotated for calculations. By using another ICCS red horizontal line level you can find your own points for 3 or 4 Leds populated.

 

[RCruz]

Thank you Salas

From what I read, IRF9610 is faster and if I do not need high currents, maybe the best choice would be to use it in both positions... right ?

 

[Salas]

Not both positions. CCS. It lacks enough transconductance for shunt position. You wrote at a point about using 9530 for CCS I saw.

 

[le´flu]

Hi everybody,
Salas recommended at the njfet thread a SSLV1.1 for the FoldedSimplistic that
should draw 200mA (CCS) at 35Vout.
The BiB-cookbook just has schematic without parts and values.
Question: is there somewhere a BOM and schematic for a BiB/SSLV1.1 that
suits the FoldedSimplistic?

Sorry for being lazy

Greetings ulf

 

[Salas]

No, it has much discussion and examples and there is an Excel calculator on first post also. Anyway, use example (e) with one led only, jumper the second led position. That will put it in the adequate voltage range to set 35V with the trimmer. Use 15R 3W to 5W for R101, R301 and 4x 1.9V leds for D102 etc. it will set circa 200mA CCS. All other non application specific parts have standard values in the guide's bom.

 

[le´flu]

Hi Salas,
thanks ... just played with the exel sheet around. At operating point V out
is 35V. CCS (Q101) is 200mA But how high is load consumption?
In the BiB sheet you recommend DC in to be about 10Volts higher than V out
- right?

Greetings ulf

 

[Salas]

Yes, 10V drop over the 1.1 reg is more than fine. Each folded simplistic channel (1x2SK369 input stage, pdf circuit) will consume ~30mA. The 170mA spare will allow for good B+ output impedance when burning on the Mosfets. In case its too hot for your arrangement and sinks, you can use 130mA CCS. It may lose a bit of subjective quality VS 200mA or 300mA, but still very nice.

 

[le´flu]

okay, sounds good. Will go and select some leds and sk170 tomorrow.
As i understand i have to use ´lytic in position C301. Which type do you
prefer? low ESR or better not? Pana FC, FM? Btw. what are your favorite
type of rect. diodes?

Thanks ulf

 

[Salas]

Pana FR,FM,FC or Nichicon Muse 220uF/50V will do. Pick your favorite. MUR120 or SBYV27-100 diodes are nice too. The big filter lytic on the reg better be select quality too. 4700uF/63V is fine.

 

[Salas]

P.S. 2SK117GR, not 2SK170BL for the reg. There have been funnies when some attempted.

 

[le´flu]

Good morning,

salas, could you please post the schematic of the plus-regulator out
of the BiB-sheet? I can´t extract it out of the pdf and would like to
have it for writing values of parts on it.

Greetings Ulf

 

[qusp]

cant you do screen captures of the pdf?

 

[Salas]

Straight from my LTSPICE schematics bank set at 35V you want.

 

[le´flu]

Hi Salas,

WOW - thanks a lot