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Lights, camera, cut traces.

A project log for Interdimensional Portal Gun

A 3D printed portal gun, which projects animated portals.

daren-schwenkeDaren Schwenke 03/26/2018 at 04:350 Comments

Working on the LEDs.

For projecting images, the brighter the better.  My target brightness was 3000 lumens.

Each one of these 5630 chips was rated at 22 lumens. 

That would be a lot of LED's, and a lot of work.

But, I got a 4 pack of these Walmart LED bulbs, for $8.

As you can see, each one is rated for 1100 lumens.  That's more like it.  Let's see what we got to work with here...

Your normal high voltage, long string of chips.  Nice small form factor though.  Yay for smaller PCB's being cheaper...  :)

I braved the blinding light and significant electrocution hazard and tested the voltage drop across most of them.  The range of measured voltage drops was entirely between 5.92v and 5.94vThat is an incredibly tight range for a $2 bulb.  That is a tight enough range in fact that I bet I can just cut some traces rewiring them into groups of two, and then run them all in parallel with a single current limiting resistor.  

So that's the plan now.   Keep these on the PCB and the AL backing plate they are currently bonded to as a bare minimum heat sink (I'll probably need a fan), and then cut traces on the PCB to rewire the LED's into groups of two.  

Building three of these will give me 3300 lumens for projection, and given the LED pattern, I may be able to get away without a focusing lens for my light source.  Bonus.

I'll also have one more left over for use as my portal fluid light, with a nice hole through the center waiting for me. 

I'll probably be grinding the AL plate these sit on down a bit so it will fit better, and instead of any real heatsink, just blowing a fan across them.

Oooo... I could use an axial PC fan for cooling these, and also have it spin my portal fluid discharge simulator!  That would give me a built in hall effect sensor if I use a fan with RPM feedback, so I then could synchronize the LED strobe rate to the rotation.  I'll still randomize it of course, but now the strobe rate could vary so it looks right at all speeds, or spinning up could cause faster discharges..  :)

I love it when a plan comes together.

EDIT: Well my 80w soldering iron was not enough to even remove the lead wires.  The heat just gets sucked away into the AL backing plate too fast. (yes, I removed the assembly from the bulb first and insulated the plate)  I also tried to separate the PCB from the AL and it's not going anywhere.   That complicates things a bit as soldering the LED's for ganging them just got a lot harder.

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