Regulators, Cases, and Heatsinks. What works? What doesn't?

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Sammas

Well-known member
Joined
Sep 30, 2004
Messages
547
Location
Sydney, Australia.
Dear band of merry men.

Here is a question for you about regulator heatsinking. Typically I just attach the regulator to the case (isolated of course), but at the moment I have a JLM powerstation on my bench with 5 regs nicely lined up. It is going to require considerable heatsinking. Originally I was going to slice a square out of the back of the case, mount a big 200mm finned heatsink off the back, and push the PCB and regulators up against it on the inside (bolted to each other, naturally). Some regulator on heatsink action. Kinky.

Is this overkill? According to the JLM psu calculator I require about a 10degree thermal resistance heatsink. The one I have in question is 5.5 degree thermal resistance. Do I really need to slice out the square of case? Can I have a case sandwich? regulators -> case -> heatsink all jammed together with bolts?

Also, what are the repercussions of overheating regulators? Thermal shutdown? Fireworks?
 
Sammas said:
Also, what are the repercussions of overheating regulators? Thermal shutdown? Fireworks?

Hello,

no fireworks-as far as I know these have LM317 and LM337 regs,right?
So they´ll limit current first and after that go to thermal shutdown.
The max. temperature is at 125 degrees celsius.You´ll know when it is becoming really hot ;).
If unsure you should have a temperature-meter handy(sorry,don´t get the english word for it at the moment-in german it is "Thermometer")-I always have one with a laserpointer (about 30 Euros) not only for checking my oven but for anything else.
A very useful tool-together with Joe´s great heatsink-calculator of course!

Attached a pic of how I do it normally.

Bye,

Udo.

P.S.:I forgot to mention that you should not forget the insulators under the regs...
 

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    PSU 1.jpg
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Thermometer is the same word in English and German, just different pronunciation. In english they say ther-mom-i-ter.

Good idea on the laser pointer... where did you get it at?  Conrad perhaps?
 
mista min said:
Good idea on the laser pointer... where did you get it at?  Conrad perhaps?

Well,the pointer is only useful to show where you´re measuring.It´s not a precision instrument but can give you a very good clue of the approximate temperature.Mine is from conrad.This one:
http://www.conrad.de/ce/de/product/100980/VOLTCRAFT-IR-260-8S-IR-THERMOM/SHOP_AREA_17210&promotionareaSearchDetail=005
They still have them stock.

Best,

Udo.
 
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