The simplistic Salas low voltage shunt regulator - Page 507 - diyAudio
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Old 28th May 2012, 12:27 PM   #5061
Salas is online now Salas  Greece
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One is CRC the other is RC. First one holds more to the Tx.
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Old 28th May 2012, 01:25 PM   #5062
AndrewT is offline AndrewT  Scotland
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What is the Vac output range of the transformer on zero load (open circuit)?

Use the lowest voltage from that range to determine the input voltage to the regulator.

I think that the 13Vdrop across the 65r is too high for a 200mAdc current output.
Try adjusting your input voltage, by adding parallel resistors to your 68r (E6 value)

Could you post a link to that spreadsheet?

On the spreadsheet:
The output voltage is specified as 21Vdc. The current as 200mA, the resistor as 65r.
Working back, the voltage on C1 & C2 must be 21 +[0.2*65] = 34Vdc.
That just about agrees with the input voltage.

In PSUDII:
Add in the first capacitor.
At present the 65r is preventing the smoothing capacitor from charging up. It's working a bit like a choke input filter without the choke. The resistor is "choking" the output.
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Last edited by AndrewT; 28th May 2012 at 01:34 PM.
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Old 28th May 2012, 07:37 PM   #5063
RCruz is offline RCruz  Switzerland
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Thank you Gentlemen

The excel file is here: http://www.diyaudio.com/forums/power...airytales.html

I added the second cap on PSUII but the improvements are slight:

Why should the current on R1 be higher than the load CCS ?
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Last edited by RCruz; 28th May 2012 at 07:41 PM.
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Old 28th May 2012, 07:42 PM   #5064
Salas is online now Salas  Greece
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Simulate for more time. Its rising as it charges up the second capacitor. Consider RC time constant in other words.
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Old 28th May 2012, 08:01 PM   #5065
RCruz is offline RCruz  Switzerland
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Now I see

But I need 120 sec to get 20Vout.... Can I use this setup behind the sslv1.1 without loosing perf ?

It seems a very slow psu.
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Old 28th May 2012, 08:25 PM   #5066
Salas is online now Salas  Greece
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No wonder with 120000uF last capacitor in that sim. Are you making PSU for a Krell?
Put 4.7mF or 10mF and sim again. I would feel fine with 2.2mF-R-2.2mF personally.
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Old 28th May 2012, 09:05 PM   #5067
RCruz is offline RCruz  Switzerland
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ups

Finally:
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Last edited by RCruz; 28th May 2012 at 09:18 PM.
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Old 28th May 2012, 09:56 PM   #5068
AndrewT is offline AndrewT  Scotland
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The RC time constant tells you how fast the cap charges up.
One RC gets just over 60% of charge. Five RC gets >95%. Ten RC is effectively fully charged.
RC = 120mF * 65R = 8seconds.
Check the plot. is the voltage on C2 >60% of final voltage at 8s?

Check the plot at 40s, Is the voltage >90% of?

Check the plot at 80s.

New RC = 65 * 470uF
10*RC ~ 13s for virtually final voltage.

But, you have to correct all these RC for the effective resistance of that 200mA load.
Just accept the PSUDII predictions, it's easier that way, provided you ask the simulator the correct questions.
It comes back to the never too old advice: Never use, nor rely on simulation software, unless you can check that the answers are going to be correct. The simulation is intended to save time. It does not teach electronics basics.
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Old 29th May 2012, 02:08 AM   #5069
agussug is offline agussug  Indonesia
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I have stock of BC550 and BC560 for Salas shunt regulator

Sellers said that these are real Philips. Can anyone tell me is these real or fake?
Click the image to open in full size.
I have these too
Click the image to open in full size.
The Batch number start with "BK". Any information on the manufacturer?

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Old 29th May 2012, 10:00 AM   #5070
AndrewT is offline AndrewT  Scotland
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PH 71 look real. Is that face painted silvery?
Notice the definition in the way the PINs are cut/punched.
None of the others show this.
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