First of all, hi all! I'm new here
Next to that, I'm also new to electronics (actually just started using an Arduino board a week ago)

And now to my question.
I've mounted a 12V LED strip in my terrarium and connected a switch and 9V battery cllip to it.

My question is realy simple, I think
Is it correct what I'm doing? Or do I need to connect a 12V power source to the LED strip?

Thanks!


Greetz,

McZlik

P.S.
Sorry if this was already asked, but I couldn't find anything

 

LEDs will run on 3/4 voltage, just not as bright, and a little, square, 9V battery will not last long. That's all.

 

Thanks for the quick answer

If I want it to run on a 12V power supply(to conserve money on batteries), but just not on full brightness, I need a PWM controller, am I right?

 

You can do that with a resistor, very simple, not adjustable. You can do a PWM circuit and that will work, too. What's your preference?

 

Resistor is fine by me, it's intended as a "Moon light" stand in, sow it doesn't has to be adjustable.

 

OK. Measure the current the LED strip uses when you give it 12 volts and we can calculate a resistor for you.

 

Ok, I'm going to do that first thing tomorrow

But according to the boxing, it should use 1.44W @ 12V.

One offtopic question, what happens if you use a higher/lower resistor then needed?


Thanks in advance!

 

Total current is .12 amps. Resistor to lower voltage by 3 volts, to get to 9 volts, is 25 ohms.
Use 22 to 27 ohms, 1 watt
Using more or less resistance will change the brightness of the LEDs. That is all.
LEDs aren't all that mysterious. They just get dimmer if you give them less current.

 

Total current is .12 amps. Resistor to lower voltage by 3 volts, to get to 9 volts, is 25 ohms.
Use 22 to 27 ohms, 1 watt
Using more or less resistance will change the brightness of the LEDs. That is all.
LEDs aren't all that mysterious. They just get dimmer if you give them less current.

Can you please explain/show how you calculated that?
And 2nd, how do you know to use a 1 watt version?

I'm trying to learn it for myself, sow would be nice to know how to

 

P=IE and E=IR

1.44 watts/12 volts = .12 amp
for the resistor, P=.12 x 3 volts
that's .36 watts
double it for a safety factor and the next highest standard value is 1 watt.