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Old 07-27-06, 08:29 AM   #56 (permalink)
bigbop
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Originally Posted by PocketBrain
The scorpion bug was operated from the car battery, but it is double-heatsinked. I did, however, manage to burn it out, but that was because I was running hot with a flat 3300mAH battery. Torture test, and it didn't make it. I think I'll double the 7805's for a 12V analog reg next time. Hey, my heatsink has two screw-holes, they can share it, and that will place them both at about the same temperature, reducing the chance of thermal runaway.


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To my knowledge, you can't place 78xx regulators in parallel directly due to the output regulation design of the device. You'll need some current balancing resistors in series with each output. Have a look at the 7800 spec sheet: http://www.fairchildsemi.com/ds/LM/LM7805.pdf and the LM350 spec sheet: http://www.national.com/ds/LM/LM150.pdf

Here is a good reference for bypass caps on power supplies: http://www.national.com/nationaledge/jul02/article.html
Half way down the page talks about the 7800 series regulators.
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