A few basic questions

[ColW]

if i may...

Brilliant forum (excuse the pun) BTW guys, very informative...but i still find myself lacking with a couple of basic points.

Making my first LED cycle lamp (for fun and to learn a bit for the future) with bits that may be odd, let me know what you think..
3w Luxeon star, mounted onto a finned heatsink i've fashioned into the right shape, Recom RCD24 0.70 driver, toggle switch and three AA NIMH batteries.
Obviously the drivers only 700ma, so i know ive limited the LEDs output before i started, but its ok for now.
The heatsinks good, when the lights running, the heatsink temp is about 23 degrees C.
With 3x 2500 mAh AA batteries, i'm getting about 1.5hrs run time

All very very basic....so the questions

Maximum volts to run one LED ?
3.6v with 3 AAs is the setup now.
Can i run 4 AAs without damaging anything ?
Taking a chance, i connected up a SLA 6V 4.5Ah battery, it seemed to run ok, but the lamp seemed much warmer...not catastrophic, but hotter.

Dimming ?
Can i dim with a normal 10K singleturn pot.
If so, do i regulate the input voltage to the driver, or the input to the LED from the driver ?
Or am i talking nonsense :thinking:

Just starting out, so excuse the (maybe) stupid questions. Any thoughts appreciated.

 

[nein166]

From the pdf here are the specs of your driver IC.​

Part------------Input------Output---Output----Dimming----Efficiency
Number--------Range----Current---Voltage----Control-----max.
-----------------(VDC)-----(mA)-------(V)---------(%)------------ ​

RCD-24-0.70__4.5-36V___0-700____2-32____Dig.+Ana.____96

So it looks like its a Buck Driver and you may want to run on 4 AA NiMH minimum. It will probably not run at 700ma on 3.6V input

Not sure of your driver board layout, but it can be set up to dim according to the pdf check it out here
Page three has a schematic for dimming setup​

 

[ColW]

Thanks nein...doh, i didnt see the minimum input voltage on the spec sheet, so that clears that up.
Dimming ?..i have the spec sheets for the Recom driver...but actually putting dimming into practice is where i'm struggling. Theory / schematics is one thing, doing it is another.

I tried an RS Components PtNo 168-140 Linear 10K pot. I used it to regulate the input voltage from the batteries...it works, but is it the right way to do it ? :thinking: