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Author Topic: Low Voltage LED Tape  (Read 531 times)

Offline ImWolf

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Low Voltage LED Tape
« on: April 01, 2018, 10:39:59 pm »
I personally gravitate towards using battery power instead of a wall wart to power a lighted model, but the majority of LED tape out there requires a minimum of 9V for decent illumination. I did some looking around though and found some 3V-5V LED strip tape from a company in China.

At first I was very happy when they quoted me $1 per meter, but shipping was actually more than the product so I ended up paying $2.35 per meter....  still cheaper than what I could find anywhere else. The tape comes in bright white, warm/soft white, and RGB in 5 meter spools.

There are 60 LED's per meter, so about every 5/8". You can also use a higher voltage power source with the appropriate resistors added. In the photo's I hooked up the spool to a CR2450 3V battery.

If you're interested, you can contact the manufacturer directly and inquire about the 2835 3V LED Tape.

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Offline Mark2000

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Re: Low Voltage LED Tape
« Reply #1 on: June 05, 2018, 11:32:54 pm »
How does the brightness of these compare to 12v strips? Is it the same?

Offline Tshark

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Re: Low Voltage LED Tape
« Reply #2 on: June 06, 2018, 08:10:18 am »
I am also using 5V LED tape for my 1/650 TOS Enterprise.  Since the Arduino compatible boards use 5V this just makes it easier.  As far as brightness is concerned, LED's need between 1.8 and 3.3 volts.  The only difference between 5V and 12V LED tape is the size of the resistor used to drop the voltage.

Here is the Amazon source I used:

https://www.amazon.com/gp/product/B01G572CAW/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1

Hope this helps

Offline simi

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Re: Low Voltage LED Tape
« Reply #3 on: June 06, 2018, 09:18:13 am »
Given that the lighting should be the same - is there any advantage to the 12v flavor?  I'd love to have all my lighting be 5v - which supports arduino, loose LEDs, and this tape (which was the last hold out) without any special converter/etc.  If that's the case, then USB would be the standard power (wall wart, PC, iphone wart, etc).  I think a USB can support at least 1 amp too (anyone?).  USB cables are dirt cheap, easy to use, and standardized for power usage.

Cheers!

Simi
« Last Edit: June 06, 2018, 09:23:09 am by simi »
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Offline LynnInDenver

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Re: Low Voltage LED Tape
« Reply #4 on: June 08, 2018, 07:02:53 pm »
Be careful using an Arduino to drive the LED tape if you're going to use it to control the LEDs; you're going to have a maximum total amperage that the chip can handle.

http://www.gammon.com.au/uno

Quote
The IO pins have an absolute maximum rating of 40 mA per pin. However in practice you should design for a rating of 20 mA to be on the safe side.

Also the following groups of pins should not source than 150 mA (each group):


    Digital pins 0 to 4 plus analog pins A0 to A5
    Digital pins 5 to 13



Also also the following groups of pins should not sink than 100 mA (each group):


    Digital pins 0 to 4
    Digital pins 5 to 13
    Analog pins A0 to A5



In addition to that, the entire processor chip has a maximum rating of 200 mA current consumption.

These figures generally refer to pins in output mode (input mode won't consume much power). So you can see that, configured as outputs, you could only have 10 pins sourcing 20 mA each (to avoid exceeding the chip maximum) and even then they would need to be spread out so that you don't consume more than 100 mA from a group mentioned above.

If you're lucky, you might be able to drive 10 individual LEDs at once through the Arduino. Any more than that, and even if the main chip does pass all the current, it's going to dramatically shorten its lifespan.

Also, you should factor in that you should basically set aside 200mA for the Arduino, even if you're not using it, to provide sufficient overhead. Thankfully, they do make 5V power supplies that can deliver 2-2.5A, designed for driving a Raspberry Pi.

Offline Tshark

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Re: Low Voltage LED Tape
« Reply #5 on: June 09, 2018, 08:45:30 am »
Very good points to remember Lynn.  On my 1/650 TOS Enterprise I am using a 5VDC/2amp wall wart to directly power the individual SMD LED's (approx 16 cut from the 5VDC LED tape), Adafruits Neopixel strips (a total of 38 LED's for the Shadow Bussards), and the Arduino board.  I did place a 1000uf capacitor across output of the wall wart to prevent start-up power spiking per Adafruits suggestion.  The only power output from the Arduino board is the data line for the Neopixels and power for three individual LED's for flashing navigation lights.  Although a voltage regulator for a 12VDC power supply is not difficult to wire, it is an unneeded complication.

The only "downside" I ran into was when I wanted to use a mirco-LED from HDA:
http://hdamodelworx.com/5-PACK-0402-SMD-WHITE-Pre-Wired-with-SOLDERED-LEAD-WIRES-and-RESISTOR-for-12v_p_103.html 

These came pre-wired with a resistor for 12VDC.  It is a simple matter of cutting off the pre-wired resistor (1 meg) and replacing it with a 470 ohm resistor for full brightness.  For my red nav light on the secondary hull I left the 12VDC resistor in place and it dimmed the LED down nicely.

 




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