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The simplistic Salas low voltage shunt regulator
The simplistic Salas low voltage shunt regulator
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Old 10th September 2012, 01:44 PM   #5301
RCruz is offline RCruz  Switzerland
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The simplistic Salas low voltage shunt regulator
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Originally Posted by jambul View Post
since it can not applied below 7v
Hi Denis

Why do you say so ?
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Old 10th September 2012, 02:04 PM   #5302
Salas is offline Salas  Greece
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The simplistic Salas low voltage shunt regulator
Its the Vgs barrier of the output Mosfet and the Vbe additions of the mirror transistors. When running a high power Mosfet at 200-300mA its Vgs is sleeping enough and it can get you near 5V when compromising the mirror for voltage, that is why I recommended 7V floor, to have room. With low Vgs TTL Mosfets things change for margins.
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Old 10th September 2012, 05:15 PM   #5303
Dr.H is offline Dr.H
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Hi Salas, asking the same question Phisci asked. I'd like to use the REFLEKTOR for my pcm63 dacs. How would I get the voltage to 5V? Or is it just a matter of building the Japanese version? Or could one actually use a reg after like 7805?

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Old 10th September 2012, 05:38 PM   #5304
Salas is offline Salas  Greece
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The simplistic Salas low voltage shunt regulator
As I wrote above it will work. Just use a 500R trimmer. The 5V Kazuo San build worked with the same IRF640 Mosfet as noted on his schematic along his preferred parts and values mods. Its not another version.
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Old 10th September 2012, 05:41 PM   #5305
Salas is offline Salas  Greece
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The simplistic Salas low voltage shunt regulator
P.S. Using a chip reg after output is nullifying the effort, no real point. It could enhance as a pre reg but its small change.
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Old 10th September 2012, 06:03 PM   #5306
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Many thanks
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Old 10th September 2012, 07:35 PM   #5307
RCruz is offline RCruz  Switzerland
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The simplistic Salas low voltage shunt regulator
Quote:
Originally Posted by Salas View Post
Its the Vgs barrier of the output Mosfet and the Vbe additions of the mirror transistors. When running a high power Mosfet at 200-300mA its Vgs is sleeping enough and it can get you near 5V when compromising the mirror for voltage, that is why I recommended 7V floor, to have room. With low Vgs TTL Mosfets things change for margins.
Ok.. it needs a 7 V floor... I use 10v floor... but it can work outputting 5v, you just need to input 5 + 7 = 12v to have enough headroom right ?
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Old 10th September 2012, 07:55 PM   #5308
disfunctionalshadow is offline disfunctionalshadow  United States
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I wonder why Kazuo-san chose the LE 820uF? Was it simply the value of the summed capacitance or that the 100KHz ESR is 5mOhms, thus 2.5mOhms in parallel?
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Old 10th September 2012, 08:12 PM   #5309
Salas is offline Salas  Greece
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The simplistic Salas low voltage shunt regulator
Quote:
Originally Posted by RCruz View Post
Ok.. it needs a 7 V floor... I use 10v floor... but it can work outputting 5v, you just need to input 5 + 7 = 12v to have enough headroom right ?
No, 7Vout as a whole is enough for hot rod even *spared current pushes Vgs up.
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Old 10th September 2012, 08:31 PM   #5310
Salas is offline Salas  Greece
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The simplistic Salas low voltage shunt regulator
P.S.

Vin-Vo is another story than VoMin, follow the normal practice with such regs. No less than 5V Vin-Vo not to goof up the CCS, 10V projecting for good measure against Tx & mains tolerance. Although you may find that this class of regs can regulate very near to Vin=Vo (one Vbe dif) the CCS will lose steam.
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