Battery powering 2 devices of differing voltages?


I have an electronic circuit that outputs is a 12-24 volt device, 125 mah. It sends data over two wires to my Arduino. Which needs 5v I believe. If I wanted to power this entire circuit from batteries would this work?

If I used 12AA batteries (18 Volts) in series I could use a simple Voltage divider to get the voltage required to run the 12V device and the Arduino (5V) Would this work? I know the numbers aren't perfect just curious if in theory their would be a problem? I assume it would all share a common ground.

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You have to have a regulated supply for the Arduino, and the input analog or digital must not exceed 5V.
You can use a potential divider of the input siganls, but to power the Arduino controller it must be a regulated supply.

The Arduino do have a Vin which is also connectd to the DC socket mounted on the PCB, but I would not supply more than 12V to it, as the on board regulator is a linear device.

Can you tell us your electronics, programming, Arduino, hardware experience?

What is the aplication?
What model Arduino?
What is the 12-24v device you want to connect to it.

Thanks.. Tom.. :slight_smile:
PS. Yes common gnd.

Thanks for the reply!

Arduino wise I have an UNO and also a Mega2560.

The 12-24v device is an RFID reader from HID. Basically the arduino will be reading the data off the two data wires in the device.

The main thing is I would like a shared battery power supply for both.

My history. I used to wire and build tube amps. I have a large amount of coding experience as well, did it for a living for many years. Just don’t have much of a grasp of digital/modern electronics. I can design a simple circuits but I have a LOT of gaps, like not knowing I need to regulate the Arduino power supply. I can do simple stuff involving LEDs and 555 ICs. Trying to branch out.

Also. I’ve got a 9V barrel plug adapter. Could I use a 9v to run the Arduino with the power plug and power the 12V device separately with 8AA batteries?

The 9V plug adapter would be ideal into the DC socket.
And if the batteries are capable of supplying the current for the RFID then it should be okay too.

Tom... :slight_smile:

It may be obvious, but ensure that the 12-24 volt rfid device outputs a signal voltage of maximum 5 volts before connecting it to an Arduino pin.

Thanks guys! I guess the extra simple solution it is!

You may find that the Data lines on the RFID are only 3.3V tolerant. You will have to logic level shift the 5V data from the Arduino to 3.3V or it could destroy the RFID reader

You can get boost DC-DC converters from 5V to 24V, if you know the current requirements of the RFID
reader you could select one of these and run everything from a 5V powerbank even.