Beginner Needs Help with Simple Circuit Design and Power Source

Thread Starter


Joined Sep 25, 2017
Hey guys,

I'm new to the forum, hoping to get a bit of help with a project that I am beginning. I do not have circuit expertise, I took an EE class for non-majors in college that I did not listen to well, so I'm trying to learn a lot now.

What I want to do: The initial goal of my project is to have a sensor detect when an object breaks the IR beam of the sensor. Prior to the beam breaking, I'd like to have an LED string be red, and then after the object breaks the beam have the LED string turn green. I'd be working with an Arduino micro-controller to program the LED string.

Eventual plan: Eventually I'd like to take my initial goal above as a single module, and create multiple modules and tie them all in together. But for right now I'm only focused on the initial goal.

Active IR Sensor (already purchased): Single Beam Photoelectric Detector Active IR Sensor

LED String (planning to buy): ALITOVE 16.4ft WS2812B Individually Addressable LED Strip Light 5050 RGB SMD 150 Pixels Dream Color Waterproof IP66 Black PCB 5V DC

Questions that I have now:
1. Simple question regarding circuit design. I'd like to power this DC project from a wall adapter (only 1 if possible). Both the receiver and the transmitter I am buying each need 12-24V power supply. I'm thinking that I should wire the receiver and transmitter in parallel to leave enough voltage for the LED if I get a 12V or 24V AC/DC power supply. Is this the right thinking? If I try to wire everything in series, I'm thinking that I'd need more than a 24V supply. Anything else to consider?

2. Thinking longer term, if I try to replicate this setup 10 times, and tie them all in together, what would be the most efficient way to connect them, given I don't have 10 wall outlets available?

Thanks in advance,


Joined Sep 17, 2013
If I try to wire everything in series,
No. That won't work.
Get a 12V supply plus a 12V-to-5V adapter (e.g. a car USB supply). Their current ratings will depend on the rated current draw of the IR system, how many LEDs you plan to have switched on at any one time, and on the individual LED current (probably~20mA).
Welcome to AAC!

Thread Starter


Joined Sep 25, 2017
So, the 12V supply such as a wall adapter can power the receiver and transmitter which would be wired in parallel, and then the 12V-to-5V adapter would be wired in series to the parallel circuit, after which the LED strip would be wired in series to the adapter? Do this sound correct?

I am planning to have a strip of approx 45 LEDs that I would power up.

Thanks so much for the quick help.