Multiple sensors power

Other Hardware General Electronics
1

Good day to you all,

Thank you for your efforts into helping us newbies into the world of electronics.

I have a question. I am planning on powering quite a few sensors most of them 3.3 (some 5) volt, some of them are on cables 5 meters long. Multiple at same time.

How can I feed extra current salary into my vcc line corrected to my power supply, as I think I am running out of power from the Arduino pins on the amount and distance of sensors. .

As I can gather as long as all the groud is common, I am good with communication. However I need that extra boost.

Any ideas ?

Thank you kindly in advance.

Gary Jurgens.

2

At 5 meters you should use external power supplies.
Grounds would be connected to each other.

What kind of sensors?

The Arudino 5V and 3.3V should stay local to the PCB.
The amount of current taken form these is quite limited.

3

The Arduino Uno can only supply 20 mA of current to drive a circuit (per pin out). If the sensors need more current than that, there are several choices you have. You can use the Arduino pin output to drive a simple transistor "switching" circuit (a 2N2222A transistor can handle 600 mA), the main drawback is that it inverts your signal (On becomes Off, etc.) or you can use an Optocoupler (like the LTV4N35 ; see Arduino projects book, project #15:"Hacking Buttons" as an example).

If your power supply used to run the Arduino is not able to handle the combined current needs of the sensor driving circuits, a separate power supply will be needed.

4

It sounds like you are concerned about the voltage drop in the wires to the sensor.

Do yours sensor use the 5V and 3.3V as a "reference"? I.e. will the output of your sensor change if the 5V or 3.3V changes?

If so:

Lets say your sensor requires 20 ma and you use #22

  • resistance of 30 meters would be 16.14/1000*90ft = 1.45 Ohms

  • Voltage drop would be 30 mv.

Is this level of "error" acceptable?

In any case:

I think an higher current supply is desirable even if it is located at the Arduino location.

I also think you will need some capacitance at the sensor.

AWG wire size Resistance per 1000 ft (ohms)
24 25.67
22 16.14
20 10.15
18 6.385