I’m making a custom built lightsaber that will be controlled by an Arduino Micro (for controlling the LEDs for the blade scroll effect).
Question: I plan on making the blade out of 90+ LEDs which will be wired in parallel down the length of the blade. The LEDs have a forward voltage of 20mA. So if I have a LED driver that is rated for 2500mA, I should be able to drive 125 LEDs theoretically? Please let me know if my reasoning is sound. Also do you think the attached LED driver would work fine for this application? Please see link below.
The driver is rated for 8.25 W which is 1 watt more than a colored christmas tree bulb. Note the flat brass colored back surface This should be mounted with thermal paste to a round metal disk attached to the end of a metal tube that forms the skeleton of the light sabor. The heat from the driver will travel down the shaft and dissipate to the air.
mirith:
It will work, but it might get hot.
Have you looked at the various controllable LED strings/ropes instead?
Also, I'm not 100% sure if that driver board is designed to control LEDs individually. I don't see a datasheet.
Thank you for the quick reply!
I looked into rope LEDs, but from what I read they aren't nearly as bright as this method.
I would just be using the driver board for power. If I had all of the LEDs wired in parallel like this:
Shouldn't the driver board just treat it like one high powered LED?
I'll be using the Arduino to control the LED's. The blade is going to have six segments of 15 LEDs that are wired in parallel. I'll have the Arduino turn each segment on/off in a row to give the illusion of a lightsaber powering on and off.
raschemmel:
The driver is rated for 8.25 W which is 1 watt more than a colored christmas tree bulb. Note the flat brass colored back surface This should be mounted with thermal paste to a round metal disk attached to the end of a metal tube that forms the skeleton of the light sabor. The heat from the driver will travel down the shaft and dissipate to the air.
Sounds good! I'll be sure to mount it directly to the lightsaber. ]
now i am thinking also about powering and linking the strings to arduino
i have seen the driver linked above: how to link it to the string and to the digital pin of arduino? we need a transistor?
Yes, you will need transistors to turn the LED's on and off. I've been doing some research on the LEDs, and the brightest LED that I found was a green one with a Luminous Intensity: 6000~16000mcd.
their viewing angle is lower than 45°
it's very difficoult to find low cost leds with that angle shipping from China or Europe
at the end i had to to choice 30° leds
Can you get the 7.2V out to the LEDs? Then you can have little strings of 2 or 3 in parallel (color dependent) cut down the current requirements by 2 or 3, get more life from a battery charge.
CrossRoads:
Can you get the 7.2V out to the LEDs? Then you can have little strings of 2 or 3 in parallel (color dependent) cut down the current requirements by 2 or 3, get more life from a battery charge.
i don't understand much the suggestion... anyway we need the 4 strings linked to digital pins to turn them gradually on
this the updated scheme, with the sound board, mini-amp, speakers and accelerometer added.
Honest question: why does this circuit work? You have four strings of 16 LEDs in parallel, being fed by a constant current driver, but no single LED goes into a runaway that takes down the string?
Nice "hilt" btw. Did you CNC that yourself (employer's machine, I assume)? Assuming that's aluminum you managed to get that a perfect finish on it.
Chagrin:
Honest question: why does this circuit work? You have four strings of 16 LEDs in parallel, being fed by a constant current driver, but no single LED goes into a runaway that takes down the string?
Nice "hilt" btw. Did you CNC that yourself (employer's machine, I assume)? Assuming that's aluminum you managed to get that a perfect finish on it.
I'm assuming your addressing "onesky" as I never posted a diagram of my circuit. I have 120 LEDs in parallel driven by an LED driver that I linked to in my first post. I did not machine the lightsaber, I actually ordered the parts from the Custom Saber Shop (website).
Chagrin:
Honest question: why does this circuit work? You have four strings of 16 LEDs in parallel, being fed by a constant current driver, but no single LED goes into a runaway that takes down the string?
i don't understand much your question can you explain more?
Chagrin:
Honest question: why does this circuit work? You have four strings of 16 LEDs in parallel, being fed by a constant current driver, but no single LED goes into a runaway that takes down the string?
i don't understand much your question can you explain more?
If you set 16 LEDs in parallel you're making an incorrect assumption that they'll share the current equally. Inevitably one of them will consume more than its share of current and it will burn out. Then when any single one burns out you still have the same total current (320ma) but that's now being shared by only 15 LEDs -- the LEDs will start experiencing a cascading failure.
Hi, the only reason that I can see soooo many LEDs in parallel without current limit resistors surviving like that is the Op was lucky to get all his LEDs from the same batch, and the volt drop is extremely close to each other.
Do you have any hot spots in the length of the sabre if you leave it on for about 5 minutes. I mean hot spots in the light part of the sabre.
