The fish pond - yes, I'm not finished with that yet. I bought a constant current regulator that was supposed to operate from 5V to 28VDC and have a constant current output of 150mA. I connected that to my UV-C LED's and was very much unimpressed with the outcome. Upon measuring the current I was reading 52mA. No, I didn't miss typing in the "1", that was it. 0.052A. I started looking closer at the website I bought this stuff from and discovered that they claimed their single LED chip had a Vf of 5.6 volts. The same exact claim was made regarding the tripple series LED chip. Three chips on a board. Looking up the manufacturers data on the LED chip it's reportedly 5.6Vf per chip. Probably no wonder why at 12VDC the LED's barely glowed and read 52mA. I don't even know how they got that much current. The sales technician said the LED's I got were the older kind with a Vf of 3 volts. OK, so that's 3 volts of headroom. That should account for something.
So I upped the input voltage to 19VDC @500mA. Still the LED's glow was unimpressive. It wasn't until I put a 24VAC transformer through a Bridge Rectifier that I was able to get - using a 47Ω resistor a current of somewhere around and just over 100mA. And at that the resistor did not get hot. I was expecting it to fry. It didn't.
So now I'm just going to build my own CC source. The LED max current is listed as 200mA but is recommended to run at 150mA. I'd be happy with that. So I'm looking into building something small that has to fit in a cup approximately 1 1/2" diameter by 1 1/2" deep. Looked at Amazon but what I was finding there just was too big to fit in. So I'm considering using an LM317 for a CC regulator. However, I'm unsure how to go about calculating for the current. I know I=1.25/R. But I'm unsure about the Vf of the LED's. I do need to test them to see what that is and I just have to knuckle down and do that. But do I need to factor that into the current? Is it like a regular LED and resistor? Or do I need to consider something else here?
So I upped the input voltage to 19VDC @500mA. Still the LED's glow was unimpressive. It wasn't until I put a 24VAC transformer through a Bridge Rectifier that I was able to get - using a 47Ω resistor a current of somewhere around and just over 100mA. And at that the resistor did not get hot. I was expecting it to fry. It didn't.
So now I'm just going to build my own CC source. The LED max current is listed as 200mA but is recommended to run at 150mA. I'd be happy with that. So I'm looking into building something small that has to fit in a cup approximately 1 1/2" diameter by 1 1/2" deep. Looked at Amazon but what I was finding there just was too big to fit in. So I'm considering using an LM317 for a CC regulator. However, I'm unsure how to go about calculating for the current. I know I=1.25/R. But I'm unsure about the Vf of the LED's. I do need to test them to see what that is and I just have to knuckle down and do that. But do I need to factor that into the current? Is it like a regular LED and resistor? Or do I need to consider something else here?