The simplistic Salas low voltage shunt regulator - Page 602 - diyAudio
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Old 12th May 2013, 11:34 PM   #6011
JimT is offline JimT  Canada
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Thanks Salas

I have it working now. I have to admit that my version had an upside down mosfet, now spotted and corrected thanks to you.

The probe is new to me, figuring it out should keep me entertained for sometime.

Jim
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Old 12th May 2013, 11:53 PM   #6012
Salas is online now Salas  Greece
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The prb=0 is for when to energize the main voltage source and the load current source for small signal AC=1 and go looking for Z domain.
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Old 13th May 2013, 01:27 PM   #6013
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Quote:
Originally Posted by Salas View Post
Maybe a datasheet error. Possibly the source of your problems if an error indeed and not a peculiar version of the type which is unlikely.
I turned arround transistors and voltage at output became 22 V
thank you Salas

then I tried to replace IRF740 used as output device and broke another STP55 - don't know If It was overheated or static blown - be carefukk with STP55 handling
the next STP55 change was done using premounted on heatsink and It was OK but the output has lowered to 14 V and the STP55NF Vgs Is 1.90 V
Is It normal a change from one type of FET to other to lead to 7 V decrease of output voltage
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Old 13th May 2013, 01:48 PM   #6014
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Quote:
Originally Posted by Salas View Post
Can you take a scope picture of its output on dummy load resistor for nominal WaveIO current at 10nS/2mV div and shortest probe ground fixture possible? I want to observe something, thanks.
Here is results.
Sorry, I do not understand how to measure in low noise environment.
Load is 13.6ohm with copper foil, and aluminium boad on floor.
Probe is putting on close to terminals as possible. Probe is set on X10. So the vertical axis is read in 10 times.
First photo shows output of Reflektor running. Second is GND noise.
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Old 13th May 2013, 01:52 PM   #6015
Salas is online now Salas  Greece
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Quote:
Originally Posted by samoloko View Post
I turned arround transistors and voltage at output became 22 V
thank you Salas

then I tried to replace IRF740 used as output device and broke another STP55 - don't know If It was overheated or static blown - be carefukk with STP55 handling
the next STP55 change was done using premounted on heatsink and It was OK but the output has lowered to 14 V and the STP55NF Vgs Is 1.90 V
Is It normal a change from one type of FET to other to lead to 7 V decrease of output voltage
As I had explained the VGS is directly deciding the current bias in the mirror. I=VGS/1K
That current is what gets converted in your passive Vref. So yes, its absolutely normal to lose voltage with less VGS type and same Ref resistors. Put a Zener or LEDS string for Vref if you want same results with many types and better drift. The ref filter capacitor is big enough for cleaning any ref.
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Old 13th May 2013, 01:57 PM   #6016
Salas is online now Salas  Greece
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Quote:
Originally Posted by Kazuo Ozawa View Post
Here is results.
Sorry, I do not understand how to measure in low noise environment.
Load is 13.6ohm with copper foil, and aluminium boad on floor.
Probe is putting on close to terminals as possible. Probe is set on X10. So the vertical axis is read in 10 times.
First photo shows output of Reflektor running. Second is GND noise.
Hi Kazuo

Better set the probe at 1X and turn the Tek TDS scope's 20MHZ bandwidth limit "ON".
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Old 13th May 2013, 09:53 PM   #6017
istvan is offline istvan  Hungary
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Hi Salas,
I am a bit lost between more than 6000 posts of this topic. I would like to build 2 regulators:
- one symmetric one for RIAA corrector (MM type) -> +-15V/30mA,
- on for my DAC, +-5V/0.5A
Which versions of SSLVSR you recommend to be made for above applications?
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BR, Istvan
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Old 13th May 2013, 10:25 PM   #6018
Salas is online now Salas  Greece
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SSLV1.1
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Old 14th May 2013, 06:59 PM   #6019
tassosk is offline tassosk  Greece
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I have a working 5v SSLV1 and accidentally sorted around Q303. All LEDs continue to glow, however I have .78V at the load now and I observe D305 and d306 LEDs continue to glow for a minute after I switch off the regulator something that did not happen in the past. Any hint on parts to replace or measure?
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Old 14th May 2013, 08:32 PM   #6020
Salas is online now Salas  Greece
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I would look if Q304 shows healthy Vbe first, also I would check the MOSFETs VGS.
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