So I finished up the PCB design, ordered boards, and populated one board. The LM3404 based current regulators work fine, but I haven’t scoped the critical signals yet to make sure there are no serious problems. I need to get an IR receiver (the missing 3 pin device on the bottom right corner of the board) and write the firmware. I think the pushbutton will be used to select different fade effects. I also need to buy some RGB LEDs, currently I am just using white 3 watt Cree LEDs. They are INSANELY bright. Once the firmware is finished up, I will post the Eagle files, gerbers, and firmware for all to enjoy.
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27 February 2008 at 10:11:40
Hey this is OHARARP…just wanted to let you know that I appreciate the link above and am looking forward to seeing more on your RGB controller. I have been looking at using the LM3404 for another project and would like to learn more about how you went about things. Please drop me a line via e-mail at ohararp at ohararp.com Ryan O’Hara
27 February 2008 at 18:30:05
Hi Ryan, thanks for joining. My LM3404 design is pretty much right out of the datasheet in terms of the component values I used. The layout is the hardest part of a good design IMO. The main points are: make the switch node as small as possible, put the cathode of the catch diode right next to the ground terminal for the input capacitor, keep the current sense connection away from the switch node. The output capacitor is apparently for smoothing the current ripples only, ie, it lets you use a smaller inductor. Six of one, half a dozen of the other if you ask me. So I just omitted the output capacitor. Anyway I hope that helps.
13 March 2008 at 18:09:46
dub any chance you could share your schematic with actual values or a bom?
13 March 2008 at 19:41:03
I’m planning on posting the entire design, layout, schematics, firmware. Need gather up my motivation I guess!
17 March 2008 at 4:52:53
sup dub! speaking of LEDs, i was bargain hunting the other day at Cash Converters here in Chch and came across this really sweet climbing headlamp by Petzl called the Duo. Big 4-AA batterypack sits on the back of your noggin, everything totally waterproof. Looks like the thing you see in Digger. As per the name, it’s got two lights. I think it was made before the LED craze in lighting took off, and I think one lamp is standard incandescent and the other may be a halogen. It just dawned on me though to look for LED-for-bulb drop-in replacements for better battery life, and there appears to be much enthusiasm for such a thing using 1W Luxeons or even 3W LEDs. I couldn’t haggle the guy down from $20 to $15 the other day, but might just go back tomorrow and say the hell with it and get it, as I’m getting excited about the whole upgrade thing. Might need your opinion on such things if it’s not gone already, and will get a Flickr pic of it up if I can seal the deal. You’ll be jealous. Stay tuned.