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Topic: Counter EMF Protection (Read 955 times) previous topic - next topic

spcomputing

I would recommend a thermal "paste" (for notebook heat sinks and high power graphic card heat sinks).  The tape will not make the best contact between the two planes (heatsink and device flange).  If sparkfun does not have it, your local computershop will.  Just look for the stuff with "silver" in it.

TeslaIaint

#6
Jul 25, 2012, 05:37 am Last Edit: Jul 25, 2012, 05:48 am by TeslaIaint Reason: 1
Does it act as the "glue" as well?
If not, what do you suggest?

edit: from a small town. no computer shop haha

radio shack maybe? but radio shack can .... .. ....

spcomputing


Does it act as the "glue" as well?



No, you will need a nut a bolt.  It very, very slowly dries out (good thing).  You would still need a nut and bolt to make the tape work.  The important thing is to make good thermal contact with the most surface.

Radioshack has this online which I repaired an overheating Mac with:

http://www.radioshack.com/product/index.jsp?productId=11300878

Same stuff that gets an extra amp or two out of my full bridge drivers.

TeslaIaint

that's the thing.....
no nut and bolt possible or else too easy...
just a small surface mount chip

Docedison

#9
Jul 25, 2012, 06:25 am Last Edit: Jul 25, 2012, 06:46 am by Docedison Reason: 1
Two things... the thermal tape will work as well as anything else... as the plastic case wasn't designed for heatsinking and has a very high thermal resistance. There is another type of motor driver that uses a big IC with a metal tab on top, that device is capable of a great deal more current. I built a valve controller that 'Worked' a three wire solenoid "Pilot Valve" about 10 12 years ago. I used one of these parts An L298 and it was directly heatsinkable... A minute of searching found these Items (There were several of them,, all shields)...< http://compare.ebay.com/like/150765336052?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar for $7.25 and the Spec sheet says it is good for 4 amps PEAK and 2.5 A @ 80% duty cycle. I scrapped the Ic in favor of a relay and an NPN transistor as the area in which my application was used was Agricultural and nearby lightening strikes took out the IC as frequently there could be 50 meters of wire between the solenoid and the controller. The issue was 'Transverse fields" or the way the energy from the strike literally electrified the earth around the device. I've measures several KV of induced voltage... lost a couple of small strip chart recorders before I totally realized the potentials involved. USE your 'browser and don't be afraid to look around. I've found that the people who make the biggest noise (Big Ad's All over the place) are the absolute WORST for prices. It should be an easy task to develop a 20 A reversible motor driver with a relay and a power Mosfet... Braking too, even to be able to use the stored kinetic energy to charge the battery for braking. It is a driver I designed many years ago for bi-polar or Latching Solenoids... I don't think I ever had one fail from anything beyond the occasional defective relay. It was a 20A Omron DPDT relay and a D44H11 transistor (Mosfets would have been my first choice but they weren't as reliable or as inexpensive as the relay/transistor combination... At that time power Mosfet's cost about 4 times what the D44H11 cost. Very reliable for my application, I made several thousand of them (not me directly but my crew did) and ALL worked without fail. Use the L298, NOT the L293... unless you are good enough to add power transistors or Mosfet's to handle the real power. Easy and Simple.

Doc
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