The simplistic Salas low voltage shunt regulator

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#2,261
With current over 200mA don't need the Rs cap, without the Rs cap sounds lower but incredible clear than the Rs cap.🙂

To use Hypno both rails + I only have to change the polarity caps & use in both rails the same BC550C instead BC560C for Q3?
 
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#2,265
Why don't you make a double + with remote p2p now that you got the knack of it, and make a pcb +/- needed somewhere else not to hack that nice board and make mistakes? Or even better make one real Hypno buffer to use somewhere, its very nice quality many builders say.
 
#2,272
Salas said:
Why don't you make a double + with remote p2p now that you got the knack of it, and make a pcb +/- needed somewhere else not to hack that nice board and make mistakes? Or even better make one real Hypno buffer to use somewhere, its very nice quality many builders say.
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merlin el mago said:
VRef 0.6V + leds:
Vout +5.5V 2 leds 1.8V = 4.2V?
Vout +7.5V 3 leds 1.8V = 6V?
Vout +-15VDC 8 leds 1.8V = 15V?
Vout +-24V will be 13 leds 1.8V = 24V?

For CCS D1+D2+D3 always 3 leds 1.8V?
Click to expand...

Instead leds Borbely uses:

VRef
LM329DZ TO-92/6.95V Low-noise buried Zener ref.
LM336Z-2.5 TO-92/2.5V Ref. Diode
LM336Z-5.0 TO-92/5.0V Ref. Diode
LM4040DIZ-10 TO-92/10V Ref. Diode

CCS
E-102 0.88-1.32mA Constant current diode
E-202 1.68-2.32mA Constant current diode
E-452 3.90-5.10mA Constant current diode
E-562 5.00-6.50mA Constant current diode
E-103 8.00-12.00mA Constant current diode

Leds are less noisy than these diodes?
 
#2,273
One red LED with a Jfet is 35nVsqHz and adds non linearly under square rt rule (rms sum uncorrelated) with population. IR LED can be a bit less. LEDS are matching the JFET impedance well to be less inclined to pick up hum fundamentals.
LM329DZ can be more than 110nVsqHz. Its stiff due to low impedance too.
For any CCS LM depends on what it drives.
 
#2,274
So it's better if I use leds for Vref:

VRef 0.6V + leds:
Vout +5.5V 2 leds 1.8V = 4.2V?
Vout +7.5V 3 leds 1.8V = 6V?
Vout +-15VDC 8 leds 1.8V = 15V?
Vout +-24V will be 13 leds 1.8V = 24V?

For CCS D1+D2+D3 always 3 leds 1.8V or wich constant current diode can be used? so I can try to see if there is any difference between the constant current diodes or leds for CCS.

While please let me know if it's ok the leds quantities for VRef & CCS?
 
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#2,275
Example 5.5V. If your Leds are actually 1.8V when 5mA-6mA is running, you would need 2 LEDS + 2 1N4xxxx diode. 4.2 from Leds + 1.3 from diodes + 0.6 standard because in those circuits Vref it is Vbe lifted. In the DAC end they use just 2 leds and a small trimmer so to get the main Voltage from LEDS and add some controlled from the trimmer drop. You got to both understand the logic and make experiments.

There is lowest noise 2SK Jfet CCS for the LEDS already. Can't recommend CCS diodes since I haven't put them there.
 
#2,276
Sorry Salas, English isn't mine native language so is possible that don't explaint me very well.

I understand that in QuangHao shunt for DAC the Vref it is Vbe lifted.

If I understand well I need to add 2 1N4xxxx (please tell me exact number, remember I'm newbie be patient) diode to reach the 5.5Vout, so each 1N4xxxx adds 0.65V, but I don't understand 2 LEDS 1.8V x 2 = 3.6V & you said 4.2V 😕
 
#2,277
3.6+1.3+0.6=5.5V so 4.2 must have been a typo.

All those are V1.0 for different purposes. I designed that also when they were asking for 5V digital reg, then they liked it and made its way in a GB.

I would advise you to follow that route, i.e. build the most Voltage by LEDS and use a trimmer to add the last part so you can easily match. Because in practice, LEDS and diodes and Vbe will be needing many iterations to match. Diodes are nearly as quiet as LEDS.
 
#2,279
Salas said:
3.6+1.3+0.6=5.5V so 4.2 must have been a typo.

All those are V1.0 for different purposes. I designed that also when they were asking for 5V digital reg, then they liked it and made its way in a GB.

I would advise you to follow that route, i.e. build the most Voltage by LEDS and use a trimmer to add the last part so you can easily match. Because in practice, LEDS and diodes and Vbe will be needing many iterations to match. Diodes are nearly as quiet as LEDS.
Click to expand...

Ok now I understand, the trimmer always 100R will be enough for all voltages?
 
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