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Old 03-27-2009, 07:59 AM   #1
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Default Stim power supply advice

I've been building my megasquirt and stim lately but need some advice on power supplys for the Stim. I've digged around my house to find what kind of 12V DC adapters i can find and i've found a few but they are all rated at over 1000mah. Is this safe to use this with the megasquirt/stim as megamanual says:

You can use the 'wall-wart' style AC/DC adapter from discarded household electronics if it has a 9 to 12 DC Volts at 300 to 750 milliAmps DC output.

Will too many mah be bad? Usually on batteries, the higher the better.
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Old 03-27-2009, 08:47 AM   #2
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The mAh rating tells you how much current the supply is capable of providing, if the load requires it. However a device will only draw as much current as it wants to, given the voltage it is driven with.

So, from a maximums standpoint, voltage matters but current does not. The car's electrical system is capable of delivering several hundred amps, but since it presents a max voltage in the mid 14s, the MS draws only a few hundred ma.

The mAh rating should be read as a minimum.
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Old 03-27-2009, 11:26 AM   #3
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I was lucky - my computer speakers use a 12V 500 mA power source, so I never had to worry about this...
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Old 03-27-2009, 11:56 AM   #4
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get an adapter from an old cordless phone.
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Old 03-27-2009, 12:35 PM   #5
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Aah thanks, I got confused between mA and mah. I'll try hooking it up tonight.
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Old 03-27-2009, 01:33 PM   #6
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Worst case you can always use a 9v. They last long enough to do all your testing.
--Alex
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Old 03-27-2009, 01:49 PM   #7
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Quote:
Originally Posted by AlexO35 View Post
Worst case you can always use a 9v. They last long enough to do all your testing.
--Alex
Thats how I run the megasquirt in my car. Less electrical noise this way. I get super smooth logs.
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Old 03-27-2009, 02:03 PM   #8
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I bet my legs are smoother....errr, oh wait.
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