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Asked — Edited

Over Heating

DJ,
I have managed to hook up alot of servos and I find that the voltage regulator overheats and the servos will no longer hold their respective positions. If I shut them down for a few minutes then everythig is fine again. I plan on making a large heat sink but I am wondering if that will be enough. Would a fan be a good idea? Has anyone done this and what kind of area should I go for on the heat sink? Any advise would be appreciated.

#1  
So I have been thinking of the same kinda thing. i have been thinking about these little guys. They look like the same size as the voltage regulators.
PRO
Synthiam
#2  
A larger heatsink may help. One with a fan will probably be best. If the servos have a lot of load, the voltage regular will suffer. An alternative option is to not use the onboard voltage regulator.

There is a solder pad on the board near the bottom right. If that pad is cut (with a razor knife) then you can provide alternate power to the digital I/O pins along the right side of the board.

Try a larger heatsink first and see what kind of results you get.
PRO
Canada
#3  
Not to discount the heatsink idea because I think it's valid but before that I would desolder the LM1084's heatsink, apply thermal compound (ex: from MG Chemicals), install the heatsink back on and try again. It's true that if you have a huge amount of load the regulator will go into thermal shutdown but with our tests we found that it takes quite a bit to make that happen when thermal compound is applied, like moving 17 servos at the same for 2 minutes straight. If you can add delays and/or move less servos at a time you will increase the time before thermal shutdown of the voltage regulator.

IMHO try thermal compound, then a bigger heatsink (with thermal compound) and if you still need more current capabilities try the external power trick that DJ mentioned, just make sure you don't supply the servos with much more than 6V cause that's the limit of most of em'. You'll want to be in the 4.8 to 6 Volt range.

Edit: So it's actually called Silicone Heat Transfer Compound by M.G. Chemicals. The tube I have has lasted me about 3 years and it looks like it'll last me 3 more years for the price of $16. I use it on my voltage regulators, CPUs, and GPUs. The thermal conductance isn't as great as Arctic Silver but it outlasts it by far.


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#5  
Hello to all,
I picked up some heatsink compound on the way home and disassembled the EZ-B just to find that it already had compound between the heatsinks and the LM 1084's. I put some more on just for good luck. I will let you know the outcome when I get it hooked up again.
PRO
Synthiam
#6  
I thought as much. I don't actually build the boards but I do recall arranging to have that grease put on during assembly. Must be happening then:)
#7  
Hello to all,
I put a small fan on the existing heatsinks and it is working fine so far. $6. 75 at the local computer store.
PRO
Synthiam
#8  
Smart! Let's see a pic
#9  
Having the same problem going to try stealing a fan from an old pc and wire it directly to the battery. Im using LiPO 4S 4200mah

Will that work? I think most fans run on 5v power and this is 14.7, do I need to drop the voltage?
PRO
Canada
#10  
Actually funny enough most PC fans run at 12V so supplying them with 14V should be no prob or you could use a 5V fan and run it off of the 5V regulated voltage, the LM1084 is pretty beefy so it can handle it.
#12  
I put one of those 5v fans on the back of my EZ-B and have no heating issues at all. Here is how DJ mounted the fan to the board.
#13  
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I picked up a VGA aluminum heatsink and 40mm fan pushing around 5 cu ft min , thermal compound is between the original heatsink and new one. I wanted this cooling solution to be completely reversable. On a EASIER idea however radioshack has excellent heatsink kits that are 2:50 each and predrilled to fit our regulars.