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On Netduino homepage it is stated that Netduino can be powered by input: 7.5 - 12.0 VDC or USB. The car output voltage is 12V but the car voltage source can produce voltage spikes so I am not sure whether it is safe to plug netduino directly into car voltage supply without any additional protection such as voltage limiter.

Does anyone know if it is safe to connect Netduino/Arduino directly to car voltage supply?

Thanks

Niko Gamulin
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    Quick and simple way to interface it: Car cigarette lighter USB charger adapter. You may already have one for your mobile phone. – Majenko Nov 16 '11 at 18:30
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    *The car output voltage is 12V* - No it's not; it's 13.8V nominal when the car is running. – Kevin Vermeer Nov 16 '11 at 19:39

3 Answers3

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No. Going strictly by the spec you quote, connecting to a car is out of spec. Even without spikes, it will be close to 14V when the engine is running. Spikes can be 10s of Volts, and unless a circuit specifically states it is designed to handle that, you must assume it can't.

Olin Lathrop
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No.

Cars can have even worse nasties than others have suggested.

NatSemi (and no doubt others) make voltage regulators designed to survive in an automotive environment.
eg the LM2940 LDO

They say

  • Designed also for vehicular applications, the LM2940/ LM2940C and all regulated circuitry are protected from reverse battery installations or 2-battery jumps.

    During line transients, such as load dump when the input voltage can momentarily exceed the specified maximum operating voltage, the regulator will automatically shut down to protect both the internal circuits and the load.

    The LM2940/LM2940C cannot be harmed by temporary mirror-image insertion. Familiar regulator features such as short circuit and thermal overload protection are also provided

Russell McMahon
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  • Russell, thanks for info. I will design the voltage limiter and connect it between car voltage source and netduino. – Niko Gamulin Nov 17 '11 at 09:06
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Besides the voltage problem you should be aware of temperature range problems of electronic parts.

f4m8
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