I have 5 1FT LED 12V light strips on a helmet. They are powered by a 9V battery. what I would like to do is make them flash at the same time and be able to change the speed of the flashing light. What do I need to complete this? Keep in mind, this has to fit an a construction workers type helmet.
Thanks for your help everybody.
A small Arduino like the Mini or Micro, 5 FETs and accompanying resistors, a pot and the rest of the work would be done in programming.
I do have an arduino uno R3’s but they only put out 5V and the light is weak. is there a way to up the power output to each LED strip?
and what is the “FET” you mentioned?
That’s what the MOSFETs are for… Google “controlling mosfet with arduino”.
What size MOSFET’s should I use?
(9V battery through an Uno to power 12V white LED strip)
That would depend on the current needed for one strip. You can measure the current draw with a DMM for one strip (which maybe the easiest), or look at the spec sheet for the strip. If you cut the strip from like, a 1 meter length, then there will be some math involved.
Teepee45140:
I have 5 1FT LED 12V light strips on a helmet. They are powered by a 9V battery.
That’s the first source of dim light. Even after you add a FET or other switching device, they will still not be at the expected brightness.
Here is the hat I have working now. It is powered by 1 9V battery and I have an on off switch. The LED’s dont give me any info on specs as they came from China. Only thing I know about them is 12V to power but I have them working fine on 9V
Then you’re going to have to use a DMM to measure the amps. You only have to do it for one strip.
First off, thank you guys SO much for your help. I’m learning alot from you all.
Here are the LED’s im using
Cutequeen 30cm LED Car Flexible Waterproof Light Strip White (pack of 4) https://www.amazon.com/dp/B00BQE5JAK/re … qwbHJCXAQB
I did notice that the package says “12DC power only”
I tried to find the amprage with my DMM but nothing came up. I probably not using it correctly.
Not sure where to go from here.
Google “Measuring current with multimeter”
SparkFun has this :
https://learn.sparkfun.com/tutorials/ho … ng-current
You’ll need to break the circuit and insert your meter. Also, make certain you have it set to a current range and you’ll likely need to change at least one socket where your meter lead jacks into your meter.
okay, i did my calculations and i think i have the amps.
4.4 amps per strip.
Check your math; no way will you get that from a 9V battery.
the fuse in my DMM was blown. Fixed it and heres what I got:
Looks like 143mA
I can’t make out the scale your meter is set to but it looks to me like 14.3 but that’s unlikely 14.3 mA for a strip.
Still somewhat of a mystery.
143 mA makes more sense but I’d swear after viewing the larger picture that it says 14.3 very clearly on the display…
Yes, it does say 14.3 but the setting may be a multiplier.
If 143mA is the correct current, then the [BS170 could do the trick.
Circuit attached. Just replace the TIP120 with BS170.](http://www.digikey.com/product-detail/en/BS170_D26Z/BS170_D26ZCT-ND/3042544)
okay so back to the original question: What size MOSFET’s do I need?
Really?