Adding power to IR sensors


I've made an installation using Arduino and 6 Sharp IR sensors.

The problem I have is that as the wires to the sensors are so long (15 meters at some points!) the power being received by each sensor is cut down and is not enough.

I therefore want to add some 9v batteries in to the circuit (probably one for two sensors, so three in total).

I'm just a little confused as to where to put in the batteries and how to ground it all.

Any help or links to a SIMPLE explanation would be great,

Bit of a novice trying not to blow the board!

Many thanks,


How much current does that sensor draw? In general the sensors draw very little current so even for 15 meters the voltage drop will not be significant.

Did you measure the voltage at the sensor side using a multimeter? Also, the main problem of this long connection distance is line capacitance and depending on the type of sensor and the frequency it is working under, you may need some sort of compensation circuit to get the sensor to work properly.

I'm trying to use 6 Sharp IR sensors (GP2D12) too. But it seems to drain almost all the power from USB cable and DC adaptor (12v, 500 ma).

I really don't know what to do.


Well a data sheet ( )
shows a maximum current draw of 50ma, so 6 of them might draw 300ma. That’s doable for a Arduino if you aren’t also powering other external components. How are you wiring the sensors to your board? What other components do you have wired to the board?


I therefore want to add some 9v batteries in to the circuit

Don't do this you will destroy both the sensors and the arduino. Both are meant to operate at 5V. It is probably not the power that is the problem but getting the signal back down the long wire.

My mistake. I made some bad connections. Now I have no more power problem. My wiring is now like this:

But something else is happening:

When I connect the IR sensors (six of them) this way, my push buttons (six) begin to behave erratically.

Maybe could be helpful to list all items I’m using:

Arduino duemilanove

Sensor Shield

6 push buttons

6 Sharp GP2D12 IR sensors

When the IR sensors are not connected the push buttons work just fine. Maybe I should add something to the IR wiring…

Does anyone have a clue about this?



Are you using analog or digital inputs for your push buttons? I had noticed that if you are reading something on an analog pin, then the voltage can interfere with the adjacent pins, so make sure they are all pulled-up/down appropriately.

This would probably also apply to digital pins if the wires from the sensors run anywhere near the pushbuttons.

Thank you very much for your replies! I haven't got a chance to test yet, but as soon as I do Il'' post the results here.

And, StevenH, I'm using the digital inputs for the push buttons.

Thanks again!!