SSLV1.1 builds & fairytales - Page 113

pellesmil · 5th May 2012, 08:17 AM

Quote:

Originally Posted by pellesmil

5deg c. in Oslo today,
Forecast says snow the next days

Greece is my solution for winter depression

Luke · 14th May 2012, 09:11 AM

Im about to order some parts, but I am looking at BL grade 2sk117, will this matter or is it a must to use the lower Idss parts?

Salas · 14th May 2012, 09:13 AM

It matters, better use GR.

Luke · 14th May 2012, 10:21 AM

Thanks Salas, I need to find some then.

merlin el mago · 15th May 2012, 11:55 AM

Quote:

Originally Posted by Luke

Thanks Salas, I need to find some then.

If you don't find ask Tea-Bag

merlin el mago · 06:09 PM

Extracted from BiB guide Rev.2:

"You could use instead a Zener based configuration. Will give a fixed low drift voltage setting. Add R303 220R 1/4W to aid noise filtering, jumper the LEDs and the trimmer positions. Use 220uF C302 50V. Not an MKT. Zeners need more filtering. There will be additional 0.6V from Q304 Vbe and R303's Voltage drop. VR303=R303*IQ303. Factor in the extra voltages. Q303 JFET will be weaker for IDSS in circuit from what you had measured with a 9V battery. A circa 4mA IDSS 9V testing JFET gives you around 3mA. If you still want keep the LEDs for indication, they will be adding their Vf too as in the first example. The higher the target Vout the more reliable a Zener reference is for low drift VS a resistor reference."

My question is: wich is the minimum high target Vout to use Zener? Zener 0.5W wich voltage? If trimmer is jumped how adjust the Vout? I ask because I'm doing regs. for 30 Vout.

Salas · 18th May 2012, 06:23 PM

The Zener option is for those choosing to avoid a trimmer. You should think of adding the Leds voltage, 1.3V from Vbe and drop on a 220R at Zener's tail, plus the Zener voltage itself to know VoutTotal.

merlin el mago · 18th May 2012, 06:38 PM

Sorry for my English, I don't understand you very well, could you elaborate?

qusp · 18th May 2012, 07:16 PM

the zener is noisier, but has a fixed voltage that is possible to be higher and possibly more stable than the largest possible total of the series LEDs on the board, so you can avoid the trimmer.

so for your total add the 1.3v drop from vbe + total drop from the LEDs + the drop from the 220r on the zeners tail for the total reference voltage

is that about right salas?

Salas · 18th May 2012, 07:41 PM

Yes, only that 1.3V represents the Vbe AND the 220R drop.

14th May 2012, 09:11 AM	#1122
Luke diyAudio Member Join Date: Sep 2001 Location: Wellington NZ	Im about to order some parts, but I am looking at BL grade 2sk117, will this matter or is it a must to use the lower Idss parts? __________________ If you give a man a fish he will eat for a day. But if you teach a man to fish he will buy an ugly hat. And if you talk about fish to a starving man then you are a consultant. Dilbert

14th May 2012, 10:21 AM	#1124
Luke diyAudio Member Join Date: Sep 2001 Location: Wellington NZ	Thanks Salas, I need to find some then. __________________ If you give a man a fish he will eat for a day. But if you teach a man to fish he will buy an ugly hat. And if you talk about fish to a starving man then you are a consultant. Dilbert

18th May 2012, 06:03 PM	#1126
merlin el mago diyAudio Member Join Date: Sep 2009 Location: Catalonia new Europe state	Extracted from BiB guide Rev.2: "You could use instead a Zener based configuration. Will give a fixed low drift voltage setting. Add R303 220R 1/4W to aid noise filtering, jumper the LEDs and the trimmer positions. Use 220uF C302 50V. Not an MKT. Zeners need more filtering. There will be additional 0.6V from Q304 Vbe and R303's Voltage drop. VR303=R303IQ303. Factor in the extra voltages. Q303 JFET will be weaker for IDSS in circuit from what you had measured with a 9V battery. A circa 4mA IDSS 9V testing JFET gives you around 3mA. If you still want keep the LEDs for indication, they will be adding their Vf too as in the first example. The higher the target Vout the more reliable a Zener reference is for low drift VS a resistor reference." My question is: wich is the minimum high target Vout to use Zener? Zener 0.5W wich voltage? If trimmer is jumped how adjust the Vout? I ask because I'm doing regs. for 30 Vout. Last edited by merlin el mago; 18th May 2012 at 06:09 PM.*

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14th May 2012, 09:13 AM	#1123
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	It matters, better use GR.

18th May 2012, 06:23 PM	#1127
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	The Zener option is for those choosing to avoid a trimmer. You should think of adding the Leds voltage, 1.3V from Vbe and drop on a 220R at Zener's tail, plus the Zener voltage itself to know VoutTotal.

18th May 2012, 06:38 PM	#1128
merlin el mago diyAudio Member Join Date: Sep 2009 Location: Catalonia new Europe state	Sorry for my English, I don't understand you very well, could you elaborate?

18th May 2012, 07:16 PM	#1129
qusp is choosing a less facetious title... diyAudio Member Join Date: Oct 2009 Location: Brisbane, Australia	the zener is noisier, but has a fixed voltage that is possible to be higher and possibly more stable than the largest possible total of the series LEDs on the board, so you can avoid the trimmer. so for your total add the 1.3v drop from vbe + total drop from the LEDs + the drop from the 220r on the zeners tail for the total reference voltage is that about right salas?

18th May 2012, 07:41 PM	#1130
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Yes, only that 1.3V represents the Vbe AND the 220R drop.

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