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my question is, I need to drop the voltage down from a car battery, probably 14v or 12v, down to 5v to power a picaxe microntroller. Would a voltage regulator work fine for this? which one would work best? Would that develope too much heat?

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Current requirements? –  Brian Carlton Feb 27 '13 at 0:47
    
Not nearly enough information. –  NickHalden Feb 27 '13 at 1:10
    
Yes you can use a voltage regulator for this. What kind (to avoid producing too much heat) depends on how much current your Picaxe uses. –  The Photon Feb 27 '13 at 1:12
    
According to picaxe.com/docs/picaxe_manual1.pdf "Power Supply: 4.5V or 5V DC is recommended. Do not use 6V, 7.2V or 9V battery packs, these could permanently damage the chip. For trouble-shooting use 3xAA cells only. 28X2/40X2 parts were also optionally available in special low power (1.8V to 3.3V) variants called the 28X2-3V and 40X2-3V. Note that 4.5V or 5V will permanently damage these special low power parts." –  Gary S. Weaver Feb 27 '13 at 20:40
    
So, should be ~1 A ? (very roughly, depending on type and how much is left in battery) according to powerstream.com/AA-tests.htm and batteryuniversity.com/learn/article/… –  Gary S. Weaver Feb 27 '13 at 20:40
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3 Answers

Get a USB car charger. Those make 5 V efficiently and are designed to deal with the nasty parts of car power. Due to the high volume these things are produced in, you'll have a hard time making something as effective and cheap. At the very least they will put out 500 mA, but a "charger" will usually put out significantly more. 1 A or more output current is common. You left out the all-impotant information as to how much current you need, but 1 A is most likely well more than what a "pixace" needs.

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yeah you will be able to find a 2+ amp 5V regulator without too much problem... if you are sourcing online check to make sure the package is what you expect it to be (I am a dumb beginner and have been surprised a few times by tiny smd versions of what I am used to).

linear or switching will work fine for you, linear uses fewer pins, switching will probably run cooler.

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I would guess a 500mA version would work for you, but for a 1 off, it is often easier to just go big –  Grady Player Feb 27 '13 at 2:13
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Just use a voltage regulator from radio shack that's for 5 volts, I know they are overpriced but it's OK because you are only getting one component so it will be fine. If it burns out, get a more powerful one. Because I don't know your current requirements I don't think a microcontroller takes too much current so an amp should be plenty, just if it gets too hot get a more POWERFUL one.

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or add multiple in parallel (linear regulators only) –  hassan789 Feb 27 '13 at 1:56
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