The simplistic Salas low voltage shunt regulator - Page 191 - diyAudio
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Old 2nd March 2010, 06:55 AM   #1901
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I built it. My oscillioscope which can show up to 20MHz and 500uV did not detect any ripples on the rails at all. It only appeared as a thin flat line across all frequencies.

It was an easy, no hassle build. I soldered the boards, connected to the raw supply, turned the voltages to the desired +-/15V, and it was done.

The new CCS is nice. It is very stable. The current is determined by 0.66V/R1. I have R1=3.9R, which gives me about 170mA. Every time I touched the heatsinks, I felt the same warmth. Never cold or hot.

The voltage drift is very small. I initially used 5k trimpot for R10 and 470uF electrolytic capacitor for C2. The drift was even smaller. But since I favoured film caps, I used 27k for R10, 2.2uF MKT for C2 (should be bigger if for full range) and put a 1k trimpot between the gate and source of the JFET, the voltage drift became higher, but no higher than 200mV, and this is more than acceptable to me.

This is rock-solid and very stable, like v1, with new enhancements in lower output impedance extending to high frequencies, even more stable CCS current, very small output caps which allow using film caps, and proper remote sensing configuration giving much higher sonic resolution.

Hi, v1 fans, you have something to do now.

Last edited by HiFiNutNut; 2nd March 2010 at 07:01 AM.
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Old 2nd March 2010, 06:59 AM   #1902
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The picture in post 1898 is only a wiring guide with perfboard. With standard ExpressBCP I can't find the symbols for the right sizes of the transistors. Note that the MOSFETs were drawn as TO-220 type but should be TO-247. I also soldered all gate stoppers directly at the MOSFET legs.

P.S. Restored to proper sizes and better layout now. The picture has been updated.
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Old 2nd March 2010, 07:43 AM   #1903
massimo is offline massimo  Italy
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Two more quick questions, Salas: RC feedback mandatory or just in case the circuit tends to oscillate? C1 (33pF) std ceramic or polystyrene or....?
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Old 2nd March 2010, 07:50 AM   #1904
Salas is offline Salas  Greece
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Mandatory. Preferably tiny NP0,C0G. Also the Vref resistor can be low ppm.
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Old 2nd March 2010, 10:31 AM   #1905
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Salas, is necessary coax cable shielded for sense wire in your "one single rail schematic for up to 60V DC out"?
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Old 2nd March 2010, 10:50 AM   #1906
Salas is offline Salas  Greece
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Yes, so to be sure there will be no noise pick up. I am going to note it on that schematic too actually. Also the LED on that schematic can be 2V as well, no problem.
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Old 2nd March 2010, 11:20 AM   #1907
AndrewT is offline AndrewT  Scotland
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where is the sense screen connected?
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Old 2nd March 2010, 11:30 AM   #1908
Salas is offline Salas  Greece
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To GND. Noted as ''sense-''.
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Old 2nd March 2010, 11:37 AM   #1909
AndrewT is offline AndrewT  Scotland
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why both sense screens to GND?
Is the +sense screen to go to GND or to a clean +ve voltage that tracks the voltage at the top of the measuring bridge?
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Old 2nd March 2010, 11:39 AM   #1910
Salas is offline Salas  Greece
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Just one coax.
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