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LCheapoSchems

L-Cheapo Mk1

Download the Gerber files here. I recommend Sunstone Circuits if you want to get it made.

L-Cheapo Mk2 and 3

Download the Gerber files here. I recommend 4pcb if you want to get it made.

The schematic is obvious, however -- the L-Cheapo only works properly if assembled according to the working drawings! Thermal conductivity is important. If you are building this on a prototyping board, be sure that the LM338 is properly soldered to the board in such a way that heat can transfer between it and the laser diode.

Do not use a single 0.7 ohm resistor instead of the eight 5.6 ohm resistors: having eight in parallel is important to let tolerances even out, and spread out the heat over a larger area.

Do not use a LM317 instead of a LM338, even if you can get a LM317 that can handle the current; the thermal coefficient is important.

Remember that the power plane in this circuit is NOT ground!

If you make this on a 2 layer board, the bottom copper should mirror the top copper (for thermal conductivity).

The design is provided for free, but on the explicit condition that you email lcheapo@robots-everywhere.com if you implement it; we can help, and we'd love a picture!

Thanks to Ruwan Janapriya for the diagram above!

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Page last modified on October 12, 2017, at 01:44 AM