Using thermoelectric coolers

[ronc]

Yo Nuuk.
The holes in the top and bottom are a type of natural convection, bu the Cu tubes will increase the performance (cooling) many fold by providing a greater thermal transfer in the sense of temp difference between the bottom of the tube and the top.The chips and Cu mounting plate will however have to be mounted as low in the case as possible for best results.I am going to run some sims and base the sims on about 40 deg C. transfer and the area of contact of the LM3875T chip wih the transfer rate of the grease included.This will give the a good idea about the size (dia & length) and the number of tubes per chip.
ron

 

[Nuuk]

Ron, I feel another GC coming on and without a suitable heatsink to hand may well try some copper tube!

 

[ronc]

Nuuk, i am working on the convection thing as we speak.I have many programs that deal with heat transfer and i believe i can design a very efficent, simple cooling device.As sated bfore i am MUCH more inclined towards ME than EE as the only courses i took in college (in EE) were required and the only time i did a elec. app. was when i couldnt figure out a way to do it mech.
ron

 

[VEC7OR]

Peltier's a.k.a. thermo-electric coolers have efficiency about 50% - to transfer 100W of thermal energy they need approx, 150W - thats the problem - you have to feed and cool the peltier too, main advantade - you can run your chips/BT/FETs at negative temp - chip amps wont clip as often as they do. For extreme cooling you can use watercooling combined with pelt's - extreme heat amount can be dissipated easily.
Copper pipes are actually heatpipes - filled with freon(the stuff in your fridge) or other similar coolant the carry heat very efficiently.

 

[ronc]

I know heat pipes and yes they are efficent, BUT much more complicated and expensive than natural convection. Any cooling needs to be easy to design into a GC case and be simple in function.
ron
Quote by one of my old ME profs."The hardest thing you can do is to make something simple".

 

[VEC7OR]

Mhm

BTW PC heatsinks are good - athlon outputs around 70w of thermal power continously, and they keep'm cool, other problem - fins are too close to allow proper convention cooling but putting a 120mm fan on them keeps them cool AND quiet.

IMO using anything more than HSF(heatsinkfan) in you amp is overkill already.

PA doesnt count - power levels at 1KV need BIG heatsinks - usually amps are placed in racks so passive(no fan etc) cooling doesnt work well there.

 

[ronc]

There are 3 basic types of natural heat transfer, conduction, convection and radiation.Of these convection is the most efficent.A norm heatsink uses all 3 if you think about it (and the HS is in the open and oriented in the correct position).The problem is that a normal HS is not really designed for efficent convection cooling.
I am in the process of running some sims for convection cooling of a chip using free convection.Using passive augmentation (a tight fitting coil in the transfer tubes which adds to turbulance of the air flow at the inside surface of the tubes which aids in heat transfer) looks like a good app.
One of the problems i have found with HS with large fins ( more surface transfer area) is vibrations.I have some HS that have many thin alum fins and are about 1" in height and mounted in the open.Its amazing that on my GC you can run your finger along the top of the fins with the amp on and there is a strong loud resonance that comes thru the speakers.
ron

 

[ronc]

BTW yall, its my birthday, 55yrs old and my GF is 32 (hehehehe).I still even have my own teeth , well 23 more payments and i will.
ron

 

[Nuuk]

BTW yall, its my birthday, 55yrs old and my GF is 32 (hehehehe).I still even have my own teeth , well 23 more payments and i will.

Happy birthday Ron but your grandfather is only 32? Are you the oldest person on this forum I wonder?

 

[ronc]

LOL, GF= girlfriend, Nuuk you crack me up.
ron
thanks man

 

[annex666]

here's a thought: if you were willing to waste 20W on a peltier, you might as well instead use 12 80mm fans. the combined CFM of which would be something ridiculous like 500CFM and still 12 fans would consume WAY less then 20W!!! (well not really, about 14.4W but still)

blasting 500CFM of air over any heatsink should be sufficient cooling

goodo
iR

Some people strive for hours designing and redesigning circuits to make the noise floor negligable - if anyone has a pc (which is pretty obvious all of you do) you'll know the kind of drone they kick out, which completely screws the noise floor.

All very well in the amp is a seperate room, but otherwise....

 

[ronc]

I agree with annex, anything you can do to keep mechanical vibrations or electrical fields (especially a vibrating electrical field) away from the chip and the components will give better results.
ron

 

[johngalt47]

Here is one guy's attempt at building a heat pipe.

http://www.benchtest.com/heat_pipe1.html

 

[Bas Horneman]

Wow.. a heat pipe is a very cool concept! ;-)

Should be easy if you can just fill a copper pipe with water and be able to suck some air out of the pipe..