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Resistor heat dissipation,,,

knockbill

knockbill

Lunatic Member
Will under chassis power resistors dissipate more heat mounted on a tag strip, or clamped to an aluminum heat sink? (Two 15W 400ohm WW dropping resistors)...
Thanks...

Regards,
John
 
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Thanks,,, That's what I was thinking also... 10W get pretty hot, so I'll use 15W strapped to a heat sink, should help em stay a little closer to spec...

Regards,
John
 
That's cute... It still would need a sink, mounting it to the chassis would probably bubble the paint...,, I'm carving out a heat sink as we speak,,, gotta fit it in the space I have...

Regards,
John
 
knockbill said:
Will under chassis power resistors dissipate more heat mounted on a tag strip, or clamped to an aluminum heat sink? (Two 15W 400ohm WW dropping resistors)...
Thanks...

Regards,
John
Click to expand...

is this a trick question ?
ok they will all dissipate the same heat or so theory says so ...:scratch2:
thing is put anyone of them real close to a heat sink and its running temp. drops as the heat is being taken away ...
how it works in practice is voodoo :sigh:
 
The Vishay's really do dissipate the heat. I have four of them bolted to the underside of my top-plate. Good thing it's polished only, it gets pretty hot where they are bolted, but the resistors are just warm to touch.

my two cents Stu
 
Knockbill,

You only have a limited number of options, all less than satisfactory. You might want to consider a way of mounting this resistor on top of the chassis in open air. If it carries high voltage, safety is an extra concern. 10w can generate quite a lot of heat under a chassis depending chassis size. At least stay away from capacitors; particularly electrolytics.
 
audiodon said:
Those Vishays have built in heat sinks. I have grown comfortable using them.
Click to expand...

Me too, you have to look at the different ratings with and without sinks, much like rectifiers and such. The amount of heat will never change, it's just a matter of how much area you spread it out over. As far as keeping the underside of the chassis cool, gravity is your friend. That's why they drill holes around the rectifier and power tube sockets, to get a draft going. You need similar intake vents too, which are best placed on the bottom cover assuming the amp has feets.
 
Yep,, I had the amp running most of the afternoon, still gets pretty hot,,, I can put my hand on it, but it puts out some heat...Good winter amp!! Plan is to have 3/4" feet , so air can circulate under from all sides....No bottom either, don't really need it for shielding, as its dead silent... If the paint doesn't discolor/bubble, its probably OK!

Maybe build the next one on an expanded metal chassis!!!

Regards,
John
 
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