Do integrated resistors in a LED make you work with an specific power source?

Aug 16, 2018
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Hello, everyone! Totally new here.

Well, I'm going to buy a pair of 12 volt "eagle eye" LED for a medicine experiment, and I planned to connect them to either a rectangular 9 volt battery or 3 cylindrical 3.7 volt batteries. But now, these LEDs are meant to be connected to a 12 volt car battery. Does the difference of the amperes between each power source (car battery, rectangular and cylindrical) conflict with the LED's functionality, or does the integrated resistor allow me to use any power source without trouble?

Here's a picture of said PCB with the integrated resistor, for example (found on the internet), it just reads "300" and I don't know what that means. Sorry if all these questions and doubts are really silly, but again I'm a medicine student trying to make this work and electricity is a really complex world. Thanks in advance, wise people!!!




Jun 3, 2018
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I hate to make your day worse but the key here is the requirements of the LED if you are trying to find a power source that will drive the LEDs. Just because the design is to be hooked up to a 12 Vdc source does not mean that they need 12Vdc.

You need to look at the specifications to determine what the actual voltage needed is and what the amperage requirements are.

You might be wiser to go to an electrical/electronic store, tell them what you are trying to do and see if they can provide you with a 120Vac LED kit that would better serve your needs.

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