Simplistic Mosfet HV Shunt Regs - Page 265 - diyAudio
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Old 30th January 2012, 12:13 AM   #2641
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Looped v+/s+ and vg/sg with jumper, and then added a 5k 10W resistor. What will the 47uF cap do?
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Old 30th January 2012, 01:46 AM   #2642
Salas is offline Salas  Greece
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The cap will decouple any inductance from input cabling, to be sure its not a bad reaction due to such at least.
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Old 30th January 2012, 02:28 AM   #2643
garbage is offline garbage  Singapore
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Hi Salas

Do I need different R3 + R4 values if I want to go up to around 150mA? Thanks.
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Old 30th January 2012, 06:28 AM   #2644
garbage is offline garbage  Singapore
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figured that out with the help of the sshv2 spreadsheet.

i can drop R5 to 1R for TP purposes, and use a R4 pot of 20R to adjust current.
R11 can be a pot of 200R to adjust voltage.

Q3 will dissipate lots of heat. a large heatsink is required.
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Old 30th January 2012, 07:34 AM   #2645
euro21 is offline euro21  Hungary
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Quote:
Originally Posted by Salas View Post
OK, fine then. Use 27-30mA CCS if you can. So 20mA goes to the reg alone. Which one of two trimmer you had substituted for fixed resistor? I think I see less than 4 trimmers on the pics.
CCS fix 20mA (blue resistor: 100R), to minimize dissipation on shunt (7mA load, 13mA shunt).
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Old 30th January 2012, 09:02 AM   #2646
Salas is offline Salas  Greece
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If your common sink isn't that hot after 30 minutes now that you can really test it, consider to spare a bit more current to boost its output performance.
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Old 30th January 2012, 09:06 AM   #2647
Salas is offline Salas  Greece
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Quote:
Originally Posted by garbage View Post
figured that out with the help of the sshv2 spreadsheet.

i can drop R5 to 1R for TP purposes, and use a R4 pot of 20R to adjust current.
R11 can be a pot of 200R to adjust voltage.

Q3 will dissipate lots of heat. a large heatsink is required.
Max CCS you can attain is based on each DN2540 sample IDSS. It may be straining to go full max of DMOS. Keep spares.
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Old 30th January 2012, 10:38 AM   #2648
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Was able to back down the drop across test point, but with inly 16V out of prefilter, i am dropping almost 12V across 220r resistor on prefilter. 500mV across R1, 3.5 across r2 of sshv2 is yielding 160 mV across r5. Diode ,easuremnets reflect gate voltages.

When i first fired it up, i fried r1 along with 220 on prefilter. Did i fry the q1 in the process?
Q2 sets the current for the SSHV2 CCS and also determines what is flowing through R5. Q1 is there just to take the heat as well as improve performance of Q2 by giving it stable opeerating conditions, correct. In my situation, with only 13V at the drain of Q1, I am reading about 100mv across R5, so that means the CCS is passing about 10ma. Great, right. Unfortunately the R in my prefilter CRC is passing almost 45mA of current, measuring about 10V across the 2W 220r. MY question is, where can this extra current be going if not through R5. FYI, the layout of my boards is an exact copy of the master, with the exception of being reversed.
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Old 30th January 2012, 11:04 AM   #2649
AndrewT is offline AndrewT  Scotland
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With HV supplies, what protects the regulator from destruction if the output gets momentarily shorted?
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Old 30th January 2012, 11:14 AM   #2650
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Zener? I am pretty sure the orientation is correct!

Last edited by buzzforb; 30th January 2012 at 11:27 AM.
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