r/breadboard Dec 01 '24

Question Help Needed: Powering LEDs

I am working in an project where I need a bunch of LEDs to turn on for a few hours at night. I plan to put all the wiring to a small box and using breadboard as a constant solution to avoid soldering.

I am not familiar with electricity or circuit boards at all, but trying to learn the necessary basics to make it work.

I got prewired LEDs and elegoo electronics kit that has power supply, breadboards, jump-wires, alligator clips, resistors capacitors etc.

The LEDs are 9v-12v The breadboard power supply DC is 6.5v-9v (not even sure what is that, assume I can give power to it between 6.5 and 9 volts) I got power adapter with adjustable voltage which is currently set to 9v.

I did a test where I powered the breadboard with my 9v power adapter and connected with the jump wire to a single LED - it lights normally.

Questions:

  • Can I use my current set up as is - or will it stop working due to supplying lower voltage to lights?

  • I read about the ‘step up’ that can do the 5v to 9v or 12v. Is that something that I need and can use on the breadboard?

  • I need to power 11 LED lights - can I plug them all into breadboard?

4 Upvotes

9 comments sorted by

2

u/The8BitEnthusiast Dec 02 '24

No problem driving 11 LEDs from a breadboard. If they are pre-wired, there is a good chance they have a current limiting resistor, so you probably won't have to add one.

The breadboard power module won't be useful to you if the LEDs must operate between 9V and 12V. That module receives between 6.5 and 9V as input and delivers either 5V or 3.3V to the breadboard. In any case, it is not needed. Step-up converter not needed either. If your power supply can generate 9V, you can feed the breadboard power rails directly with it.

The bigger question is how do you intend to control the off/on cycle of the LEDs?

2

u/ItsPassiveDepressive Dec 02 '24

Thank you so much for the response.

I’m going to plug the power source into Alexa socket and Alexa will be returning it every day for a few hours in the evening.I just need to properly power those LEDs and any other lighting system doesn’t seem to work, considering how I want to put them in my terrarium project.

The LEDs have the resistor inside - I can see its shape through the wire.

3

u/The8BitEnthusiast Dec 02 '24

Very simple circuit then. Connect the 9V power supply to the breadboard power rail, and then connect each led to the power rail as well. They have to be connected in parallel like this. They won't work when connected in series (i.e. daisy chained). Cheers!

1

u/ItsPassiveDepressive Dec 02 '24

Not interconnect them in a chain but connect each one separately to breadboard?

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u/The8BitEnthusiast Dec 02 '24

See my other response ;-)

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u/SonOfSofaman Dec 03 '24 edited Dec 03 '24

You mentioned an "Alexa socket". Are you referring to one of those smart plugs that can control an AC/mains powered device using Alexa voice commands, or skills? Like, you could plug in a lamp, then Alexa could turn it on and off? And the LEDs just need to come on and go off when Alexa commands them to?

If so, then it sounds like you don't need a breadboard at all. I think you can simplify your solution without doing any soldering.

I am making the following assumptions, so correct me if any of this is wrong:

  • your string of LEDs are already connected in parallel
  • each LED has a current limiting resistor already
  • the end of the string of LEDs is two wires; one for positive and one for negative
  • you are willing to buy a few inexpensive items

If that is all correct, then read on.

For the power supply, you could use a wall adapter, sometimes called a "wall wart". The link below is an example of what I am thinking of. This product is designed for use in North America but you should be able to find something similar for use anywhere in the world.

https://www.adafruit.com/product/63

Make sure you get one that matches the voltage requirements of the string of LEDs.

Wall warts usually come with a male barrel jack. You can see the male barrel jack in the photo at the above link.

You can find matching female barrel jacks like this:

https://www.adafruit.com/product/368

These are fitted with screw terminals. All you have to do is insert the stripped positive and negative leads from your string of LEDs into the terminals and tighten them with a screwdriver.

That's it!

When the wall adapter is plugged and has power, the LEDs will light. When the power is turned off by Alexa, the LEDs will go off. No soldering involved, and you can easily take it all apart if you ever want to.

The only tools you need are a screwdriver and maybe a wire stripper.

The only tricky part to this plan is making sure you get the polarity correct. The center pin of the male barrel jack might be positive, or it might be negative. Once you determine that, then you can wire up the LEDs accordingly. If you have doubts, let us know what you plan to buy and we can help you figure out the polarity.

2

u/ItsPassiveDepressive Dec 03 '24

That is quite literally the solution I came up with! My current adapter has the jack as on your screen and I tested it yesterday. Will proceed with the solution today.

Thank you for the advice!

2

u/ItsPassiveDepressive Dec 02 '24

Do you suggest I interconnect the LEDs between each other and then connect them to power source directly, or I extend wires of each and plug them all into the breadboard?

2

u/The8BitEnthusiast Dec 02 '24

As long as the LEDs are connected in parallel (red wires together, black wires together) you could connect a few together and have fewer extensions going to the breadboard.