Help translating and/or sourceing electrical components for the LED headlight project

[81xsproject]

So, as many of you may know, I am attempting to build a 2400 lumen LED headlight. Last time I posted I was looking for answers on building a constant current power supply. Well, I have finally found one that is perfect. The problem is that the bill of materials is the language of electronics that I do not speak very well. So, I was hoping someone could help me translate and source the parts from digikey. For instance, I can manage that R2 on the larger circuit is a .068 Ohm resistor. However, R2 on the smaller circuit is listed as 3k75... Is that a 3000 ohm, 75 Watt resistor...?

Here is the schematic;



And here is a link to the bill of material:
BOM

I am still paint by numbers, but am trying to learn. Thanks

[cywelchjr]

The 3K75 refers to 3.75K Ohms. Something somewhere should refer to what the wattages are supposed to be for the resistors. These are generally all the same unless marked differently for specific ones.

[b.walker5]

The wattage of the resistors will depend on the overall current draw of the circuit, however this circuit to do the same thing http://www.st.com/stonline/products/...e/bd/14666.pdf shows the resistors as being smd's so simple carbon film 0.5 watt items should do the job nicely for you, however if your not familar with the jargon of electronics and such it might be better for you to consider buying the whole board as shown in the link.

[81xsproject]

The board in the link is not for sale. It is a reproduction of the very popular but spendy "Buck Puck" from Luxeon. I need 4 of these boards to run all 12 of my LEDs due to the 3.6Vf required by each. At $20 each, that is not feasible considering I can build it myself (with a little help) for much less. The most expensive component is U1 at around $3 each. Plus, enjoy these projects and become a little more knowledgeable every time. The next learning phase will be adding a 555 timer to make the low beam setting a flashing headlight. I will be back with more questions for sure. Thanks

EDIT;
Oh...you meant the board in YOUR link. I will check out it's price.

[81xsproject]

YYYYYeeeeeaaaaaahhhhh...... They want $64 for that board. I'll build my own.

[b.walker5]

Okay, I completely understand, I enjoy "breadboarding" and kitsets myself. One question though..... Adding a triple 5 would be easy but why on earth would you want a flashing headlight... and yeah, 64 bucks for that would stop me dead in my tracks too ..

[81xsproject]

Haven't you seen guys running headlight modulators (in the daytime, of course)? The pulsing headlight just makes you more visible/noticeable to other drivers.

[b.walker5]

Nope... havent seen that. Hell, we've only just last month had new rules forced on us making daytime running lights mandatory on bikes. When I first got my US imported SG it had "day" lights and I disconnected them to take the load off the genny. Had to use a switch block off a 750 to get a light switch. Can't see me ever wanting a "flashing" one.

[cywelchjr]

Nope... havent seen that. Hell, we've only just last month had new rules forced on us making daytime running lights mandatory on bikes. When I first got my US imported SG it had "day" lights and I disconnected them to take the load off the genny. Had to use a switch block off a 750 to get a light switch. Can't see me ever wanting a "flashing" one.

Not flashing, but varying in brightness. It makes a bike much more visible to autos in the daytime, as the flickering of the headlight gets their attention. They have pretty much been proven to make a rider safer. I believe they are legal in all US states, in daylight, but not at night which means that all the commercial units I know of have a light sensor to disable them after dark.

I mean, I'm for anything that makes me more likely to be seen by cages, as that means it's a little bit less likely that they will take me out.

[b.walker5]

Okay, that makes sense but I dont think i'd use a triple 5 timer to achieve it. I'd probably have a capacitor and resistor combo that provides full voltage on capacitor charge up that slowly bleeds off thru resistors to a pre-determined lower threshold and then charges again, which would produce a "sine wave" effect on the DC output voltage. The frequency of the "sine" would be determined by the resistor values and a bypass circuit for night time use would be a simple as a LDR and a relay. A triple 5 would give more of an on/off effect and would require extra transistors to create the rising voltage needed for the effect. JMO.

[81xsproject]

I don't think that would work with LED's. The voltage needs to remain mostly constant. The only variable is the current which is set by R2. I believe my LEDs can be run from 80 lumens@350mA to 210 lumens@1000mA (with good heatsink). The resistor calc is .1/I=R. I plan on running them at 900ish mA.

[cywelchjr]

I don't think that would work with LED's. The voltage needs to remain mostly constant. The only variable is the current which is set by R2. I believe my LEDs can be run from 80 lumens@350mA to 210 lumens@1000mA (with good heatsink). The resistor calc is .1/I=R. I plan on running them at 900ish mA.

So I would recommend if you do the flashing type thing to vary the resistance in the line using the triple 5, then it will fluctuate just like the real lights with a modulator.

Is it just me, or has anyone else noticed that the smilies seem to move from post to post so you have to actually look and FIND the one you want? Seems like there is a randomizing to the order they appear in.

[psycoreefer]

I'm sure you've already thought of this but make sure you look up the federal regs for modulators. I know yours will be home built and if it comes down to it you'd have a tough time proving you're meeting the rules but if your at least aware and close to the rules your less likely to run into that problem to begin with. I know they state how fast it can "blink" and I think something about the max % difference between the high and low settings.

BTW I hope you post up a build thread of this headlight when your done. I'm super interested....

[b.walker5]

I don't think that would work with LED's. The voltage needs to remain mostly constant. The only variable is the current which is set by R2. I believe my LEDs can be run from 80 lumens@350mA to 210 lumens@1000mA (with good heatsink). The resistor calc is .1/I=R. I plan on running them at 900ish mA.

Doh, my bad, of course your right. Was thinking incandesant not led. Cy's right, a triple 5 would work, but then you'd already figured that out

[81xsproject]

So I would recommend if you do the flashing type thing to vary the resistance in the line using the triple 5, then it will fluctuate just like the real lights with a modulator.

Do you know how to set the 555 up to vary the resistance?