Simplistic MosFET HV Shunt Regs

Safety question

Hello

This might be slightly OT as a general question but as it concerns this build that might be built by many people that like me is not educated in all saftey rules and regulations, I thought it might be proper to ask here. Eventual answer might even serve as a reminder for others.

Regarding a high voltage FET as IRF840 in this case and the outboard placement of the fairly big sink. What is considered enough saftey rearding that? Is it mandatory to place it completely inside and insulated from a grounded metal case or can the sink be touchable from outside the case if both the sink and the case is properly grounded?

Best
Staffan
 
Read this sticky thread from tubes forum regarding safety. Will link it in post#1 here too.
http://www.diyaudio.com/forums/tubes-valves/30172-safety-practices-general-ultra-high-voltage.html

Yes, thats wise. Its a long and mixed thread with various tips, trix and examples tho and maybe its not self-given for everyone not to mount a HV FET, even with isolation pads so its sink is touchable even if grounded.

When reading I came to #49 that said: "UL specifies a minimum of a 4 mm spacing across a surface (PCB) between any "energized" part up to 400 V Peak and a part of opposite polarity or a "dead metal part" (earth). UL then specifies a 8 mm spacing for any voltage up to, I believe 1000 V peak.
"

I dont know what UL is, some countrys recommendations maybe but I think that clearly specifies that also isolation of the sink from being exposed to small fingers or whatever is mandatory.

Staffan
 
Salas,
Does this look OK? IT will fir on a standard PCB etch board available here through Radio Shack.
 

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They should be tied at the respective load points after covering the wiring distance. Else you got no ''remote'' but ''local'' sensing. I.e. A classic two wire connection susceptible to wiring length deviations in measuring and counteracting the correct impedance point by the regulator's error amplifier.
 
Dont have the mounting bar for the heatsink. Left it at the shop. Will not know till Tuesday. After my initial panicked failure first time around, I decided to take things as they come and try to be patient. I work much better this way, and tend to bother forum members less. :D

Side note. How influential are parts like resistors and caps in tthis circuit?
 
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