Well I’ve looked through all my boxes of dead parts and all I can find is 5K & 10K pots. With a 10K, the drivers will dim from minimum, up to only a very moderate level. Open circuit on the DIM wires goes full output. I suppose I could test it with fixed resistors and measure the output current, but… I’m lazy. 100K will work. A little ‘wasted range’ beyond WFO is OK, not reaching full brightness would be a bigger deal.
These also have a separate RSET input. The datasheet shows it used with a fixed resistor to set the output current (0ohm = 1000mA, 47K = 2750mA, but it’s non-linear). They also have an input for a remote thermistor but as long as the heatsink doesn’t get hot enough to catch fire or desolder itself I don’t really care. If that happens it needs a bigger heatsink, not current limiting.
FP, thanks for the Mouser link! I haven’t ordered from them before.
Good luck with your project! I think you’re going to be VERY impressed. I’ve been using a 97 CRI 100 watt Bridgelux in my bedroom and its nothing short of astounding. The entire room gets blanketed in bright even light with no shadows.
I already have one of those generic articulating lamps over my workspace, retrofitted with a $8 Chinese COB LED on a P4 CPU heatsink/fan and ‘just’ a 50W dimmable driver. More than about 1/4 brightness and it melts my eyeballs out.
Its hard to beat the virtues of powerful even lighting in the work area. And once you’ve experienced it, its hard to go back. My single 100W Bridgelux sits quietly in the corner of the room pointed up at the ceiling, and the amount of reflected light makes the entire room seem like a warm sunny day. 30k lumens of XM-L2 flashlights bouncing light of the ceiling dont even come close, even though they collectively have far more lumens. I cant imagine how bright the 100W COB would be if pointed directly at a close range target. I keep thinking “bike light”, but the COB would lack the range I currently enjoy and would require a substantially heavier cell pack. Im still mulling over the possibilities… like 3 or 4 MT-G2’s (the mini COBS with a dome).
Will you be posting pics of your finished project?
I have the drivers. I thought I had an old lamp to use for the project, but it has mysteriously gone missing after sitting undisturbed in a corner of the basement since at least the mid-'70s (possibly much longer than that, it was already there when we moved in). I'm still trying to get a straight answer about what happened to it. The explanations so far make no sense since the other similarly aged things in that area are still there and haven't been moved. I am not happy.
If some old things had disappeared, it might make sense. Everything else is still there. Only thing missing is the old cast iron lamp base & shaft. I have been told no one has any idea what happened to it, but that it definitely wasn't thrown away (see what I mean about answers that don't make sense?). Mom (not wife) wouldn't throw away anything that looks old anyway, her house looks like a fking Cracker Barrel.
I hear ya. Im the type that will tear apart the house when things go missing and wont relent until I find what Im looking for. Its such a pain in the arse! Some of those old cast iron relics are pretty awesome and I hope it turns up.
I should have looked more closely at the specs. The TE pot we discussed is not logarithmic. I called TE tech support and they dont have a logarithmic pot with those specs or anything similar. I also searched and could not find a 75K or 100K switched pot with a logarithmic taper that can handle the switched AC power requirements (although a small relay could probably be used to switch the AC). Too bad becasue I have a few projects that could have benefited. Looks like I will just keep using the logarithmic pots and toggle switches for now.
YMMV, but logarithmic makes the adjustment more linear to the eyes. Otherwise, a linear pot doesnt start to dim till most of the travel has been used, then it becomes very sensitive to the smallest of adjustments near the end of the pots travel.
What difference does the wattage rating make? Also, is there one out there with wire leads that I can just plug into the Purple and Gray input? Thanks!
Call the manufacturer of the lamp and ask their tech support. If that fails, get the part number and manufacturer of the driver/board inside the lamp and search for it online. The spec sheet will tell you if the driver can be dimmed by a potentiometer, and if so, which rating is recommended.
I hear ya. Im the type that will tear apart the house when things go missing and wont relent until I find what Im looking for. Its such a pain in the arse! Some of those old cast iron relics are pretty awesome and I hope it turns up.