It will work. Forward voltage is likely to be slightly less than 2.9 volts if running at 500ma instead of 700ma. Led data sheet should have chart with this info. But that driver has preset current of 500ma, so that’s what it will put out. You need to wire enough leds in series to fall into driver output voltage range. Series circuit voltage is additive, so 1 led 2.9v then 2 leds is 5.8v 3 leds is 8.7v and so on. In order for circuit to work properly the voltage total needs to fall within 15-24v range of driver.
There is probably some videos that would make more sense of how drivers work. Give me a chance to look.
Ok, ok. Speaking only of constant current drivers and LEDs in series, you need to have enough LEDs so the total voltage is in the range of the driver.
For the PLM-12-500, it’s CC at 500ma, and it’s voltage range is 15-24v,
If the LEDs are Vf=2.9v @ 500ma, I’d need (n= LEDs) 15 <= n*2.9 <=24 (plus/minus for margin).
15/2.9=5.1, so minimum amount of leds has to be next whole number, which is 6.
24/2.9=8.27, so maximum amount of leds has to be next whole number lower.
Plm-12-500 will run between 6 and 8 leds that have forward voltage of 2.9. You just have to check what the forward voltage is at the operating current you are running. It’s probably lower at 500ma than at 700ma.
Ok! I did it. Two triple far red plus one single photo red, mounted to a 1" sq aluminum bar. Sorry, no in-process photos, but below is a photo of it mounted to the bottom of my light.
MEAN WELL APC-12-700
CREEXPE-DRD-1*
Board Configuration : Single 1 Up
Color : Photo Red
(one)
Cree XLamp XP-E High Power LED Star
CREEXPE-FRD-3*
Triple 3 Up - Far Red
(three)
Total cost, incl. tax but not incl supplies (hookup wire, thermal paste, wire nuts, zip ties, screws, TapMagic) or tools (soldering iron, drill, bit, tap, solder, flux, hammer, center punch) came to $46.70 for a 12w 650nm/720nm 36" bar that fits reasonably well underneath a HLG Scorpion Diablo.
This was definitely not cheaper than the 7W $29 (+ $8 power supply) RapidLED Far Red Initiator Puck. But for a few dollars more, at least 50% more far red (and expandable).
AND, I did it myself (with @dbrn32 's help, of course).
This is the route I prefer 9 outta 10 times. I mean I get when money’s funny, but thats when u just dont buy things. Patience (and a friend in the lighting game ) typically rewards you nicely. Just dont give @dbrn32 the keys to the wallet… you’ll have a grow room they can see from space!
) typically rewards you nicely. Just dont give 