Protecting my arduino against high voltage spikes?

[h]

Newbie, I'm afraid, though I'm not doing badly so far.

I've built a digital speedo with an arduino and some LED displays. It picks
up pulses from a hall-effect device I've stuck by the drive train of my
truck. Currently, the output of the device (which handily bounces between 0
and 5v) is connected straight to an input pin on the arduino, but I'm
concerned that because the wire runs near the high-voltage ignition cables
for the engine, it may pick up some spikey noisy stuff - is there a basic
way I can protect my arduino from trouble?

Many thanks

h

 

[Tom Biasi]

"h" <hathowiemdotnet@deletethis.com> wrote in message
news:6b_Kl.22931$OO7.14473@text.news.virginmedia.com...

Newbie, I'm afraid, though I'm not doing badly so far.

I've built a digital speedo with an arduino and some LED displays. It
picks up pulses from a hall-effect device I've stuck by the drive train of
my truck. Currently, the output of the device (which handily bounces
between 0 and 5v) is connected straight to an input pin on the arduino,
but I'm concerned that because the wire runs near the high-voltage
ignition cables for the engine, it may pick up some spikey noisy stuff -
is there a basic way I can protect my arduino from trouble?

Many thanks

h

You could start by using grounded shielded cable.

Tom

 

[Jasen Betts]

On 2009-05-02, h <hathowiemdotnet@deletethis.com> wrote:

Newbie, I'm afraid, though I'm not doing badly so far.

I've built a digital speedo with an arduino and some LED displays. It picks
up pulses from a hall-effect device I've stuck by the drive train of my
truck. Currently, the output of the device (which handily bounces between 0
and 5v) is connected straight to an input pin on the arduino, but I'm
concerned that because the wire runs near the high-voltage ignition cables
for the engine, it may pick up some spikey noisy stuff - is there a basic
way I can protect my arduino from trouble?

connect a 100K resistor between the end of the wire and the processor
pin. if you're picking up noise from the ignition add 10nf from the
chip's input pin to ground.

 

[default]

On Sat, 02 May 2009 16:05:22 GMT, "h" <hathowiemdotnet@deletethis.com>
wrote:

Newbie, I'm afraid, though I'm not doing badly so far.

I've built a digital speedo with an arduino and some LED displays. It picks
up pulses from a hall-effect device I've stuck by the drive train of my
truck. Currently, the output of the device (which handily bounces between 0
and 5v) is connected straight to an input pin on the arduino, but I'm
concerned that because the wire runs near the high-voltage ignition cables
for the engine, it may pick up some spikey noisy stuff - is there a basic
way I can protect my arduino from trouble?

Many thanks

h

Input protection diodes are common on most pics, but it wouldn't hurt

to have a pair of external ones to suppress above supply and below
ground spikes.

Your power supply should also be safe for automotive use.
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