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crazy idea about cooling transistors

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WaveRider

Fri Feb 17 2006, 10:15AM

Registered Member #29 Joined: Fri Feb 03 2006, 09:00AM
Location: Hasselt, Belgium
Posts: 500

Hazmatt is right about DI water. For this reason, you should never drink it. If you drink DI water in enough quantity, it will deplete your body of critical electrolytes very quickly. (Something I learned working with semiconductor fab people...)

Dr. Shark

Fri Feb 17 2006, 11:05AM

Registered Member #75 Joined: Thu Feb 09 2006, 09:30AM
Location: Montana, USA
Posts: 711

What you are getting at is called Osmosis, and while the effect is real, the conclusion "don't drink DI water" is again BS. In fact there is a whole "stay young forever" movement of people who _only_ drink DI without any ill effects.

Sorry, not trying to flame people here, just setting straight the facts.

Bjørn

Fri Feb 17 2006, 11:47AM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

Health risks from drinking demineralised water (.PDF)

I would not worry too much about it, people often drink worse. If you have a choice it would be better to drink something else.

AndrewM

Fri Feb 17 2006, 01:51PM

Registered Member #49 Joined: Thu Feb 09 2006, 04:05AM
Location: Bigass Pile of Penguins
Posts: 362

I'm a little confused about this DI water / stealing your electrolytes thing. Its not like you have all your ions sitting ina an ion pouch; i mean theyre in your body dissolved in water already. I find it hard to believe that adding additional solvent causes them to magically disappear.

The only problem I could imagine would be simply drinking too much water, of any kind.

WaveRider

Fri Feb 17 2006, 02:27PM

Registered Member #29 Joined: Fri Feb 03 2006, 09:00AM
Location: Hasselt, Belgium
Posts: 500

I don't think anyone ever said it was deadly in anything less than enormous quantities..like normal water, I guess. As far as I understand it, it tends to upset the body's electrolyte balance if taken in large quantities...particularly in the intestine.. When you drink DI water, Ca, Fe, Na, MG, etc. ions are exchanged out the blood and tissues of the intestine. DI water also does not replace this passed out through the kidneys.. Of course, drinking DI water with your meal is probably OK, given the minerals in your food...altho' I prefer a glass of red wine!

The semiconductor guys I worked with also said DI water had the tendency to dissolve metals readily...so it paid to be careful! Plus, it is very bad practice to drink laboratory solutions!

Water is indeed a powerful solvent!

Oh...and by the way..I attach nice aluminium heatsinks to cool my TO-3 transistors...using a fan, if necessary! :)

Steve Conner

Fri Feb 17 2006, 04:01PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

I have also heard about problems with DI water in RF amp cooling systems. Seemingly it would corrode things like capacitors and tube anodes faster than ordinary water. Kind of a necessary evil though, since in high voltage tube circuits, DI water is needed for its low conductivity.

I doubt the transistor would last more than a couple of days, no matter whether you used DI or normal water, and I also doubt it would be _that_ much better than just bolting a water cooling plate to the TO3 mounting flange, but it's still a pretty el1te hack

HV Enthusiast

Fri Feb 17 2006, 04:08PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

Steve Conner wrote ...

I have also heard about problems with DI water in RF amp cooling systems. Seemingly it would corrode things like capacitors and tube anodes faster than ordinary water. Kind of a necessary evil though, since in high voltage tube circuits, DI water is needed for its low conductivity.

Actually, distilled water is rarely used in high voltage tube circuits for cooling. Every high voltage tube system i've worked on (both ground and sea based) use demineralized water and usually on the ships there is an extra apparatus to remove any additional oxygen that is in the water. Distilled water isn't adequate enough for these applications.

Steve Conner

Fri Feb 17 2006, 04:52PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Is there anyone out there who can explain the difference between demineralised, deionised, and distilled water? Get it right and win 12 geek points and a cookie.

Madgyver

Fri Feb 17 2006, 05:57PM

Registered Member #177 Joined: Wed Feb 15 2006, 02:16PM
Location: Munich, Germany
Posts: 214

Well like the name, distilled water has been distilled, demineralised has (almost) all traces of minerals removed and diionised water contains virtualy no Ions except H+ and OH- from natural dissoziation, which is neglible.

Marko

Fri Feb 17 2006, 07:40PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Distilled is any water heated up to boiling point, then cooled down in order of purifying.
Demineralised is water that got rid of any minerals (salts) that would increase number of ions, and deionised is usually distilled water pssed trough acidic and base exchangers, where metallic kations are replaced with HË‡3O+ and in base exchanger non-metalic kations with OH- group. These two ions tend to merge and form two molecules of water, and now we get H2O in its purest form

That water in reality gets new ions fast, from air, surroundings, etc. its usually very hard to keep deionised...

As I said at the beggining, for prolonged life of transistor and even keeping it from damage mineral oil could be used, its heat conductivity is lower but it can withstand high voltages, wont get ionised (conductive) over time like water, also there is no danger of corrosion if air is let in.

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