Powering sensors for dummies

Hello,
I've got a very basic question which I'm sure you can help.

I've got a very simple sensor V+ 3v , ground and signal output.

Everything works correctly.

I wish to replace the voltage in and the ground with a cell coin battery.

What do I need to do?

p.s. what I tried is simply run the sensor from the arduino board making sure it's all correct. then plugged the v+ and ground to a coin cell. Using a multimeter, I'm getting the same voltage reading from both the regulated voltage from the board and the battery, however, the sensor doesn't seem like being 'powered'.

Thank you in advance.
Zudiosol

zudiosol:
I wish to replace the voltage in and the ground with a cell coin battery.
p.s. what I tried is simply run the sensor from the arduino board making sure it's all correct. then plugged the v+ and ground to a coin cell. Using a multimeter, I'm getting the same voltage reading from both the regulated voltage from the board and the battery, however, the sensor doesn't seem like being 'powered'.

My crystal ball tells me from that (from your wording) you have not conencted the ground on the sensor to your Arduino (ground) when you conencted the coin cell. That is a basic misunderstanding of electrical theory.

If that has not instantly solved your problem, then you need to follow the basic rules of human communication, which cite that (given the fundamental physical limitations of the crystal ball,) it is necessary to describe why you wish to use a coin cell, and what "doesn't seem like being 'powered'" actually means in the Real World.

Thanks Paul...it did solve my issue immediately.

I know this is very basic...the sensor is a simple hall-effect.

I'm connecting the output to a small speaker and can 'observer' the changes when there is a magnetic field around.

When I connect the board 'power' (V+ and Ground) to the sensor from the board and the data output to the speaker it works fine.

When I connect the coin cell (V+ and Ground) to the sensor, ground to the board (as advised) and output to the board it works fine.

When I connect the coin cell (V+ and Ground) to the sensor and output to the speaker it doesn't work.
Based on your suggestion, I attempted to connect the coincell ground to the output in addition, but didn't have much luck.

More thoughts? (hopeful with the same crystal ball ) ; - )

zudiosol:
When I connect the coin cell (V+ and Ground) to the sensor and output to the speaker it doesn't work.

Output to the speaker...?
A speaker needs a fluctuating input to create sound. A steady DC output from a sensor would do not much except creating a small "POP" sound when connecting/disconnecting.
Also i'm quite certain that the power of the output isn't high enough to power the speaker. The output of most sensors is somewhere in the few milliAmps. You need an amplifier at least!
What type of sensor are you using?

Any other thoughts how do I power a hall-effect sensor with battery without a board?
what would be the schematic/connections for it?
Thanks.

The problem is that the battery has a DC current, and for a speaker you need an AC signal. You would need some kind of transistor (I’m not an electronics expert, I get what you want to build, but just hooking the speaker to the battery with the hall sensor in between is not going to work)
I guess you need a portable device. So the thing you need is some kind of tone generator with an oscillator for the alternating current (AC) that creates the tone.
Take a look at this link, this should help you somewhat. 555 timer IC’s are very common.

Your hall sensor would take the place of the 10k potentiometer with an extra resistor

Thankyou. This helps.