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The Quick Question Thread
Posted: Wed Sep 20, 2017 2:15 am
by Jimmy Jam
I, and others I'm sure, are going to have a bunch of little questions and maybe it'd be best to keep them in one thread so we don't clutter up the forum.
The motto of this thread is: THERE IS NO SUCH THING AS A STUPID QUESTION. So that people don't hesitate to ask, so the vibe stays positive and helpful, etc.
LED Ribbons/Resistors/CV&CC
Posted: Wed Sep 20, 2017 2:23 am
by Jimmy Jam
Okay my first question is about LED ribbons, specifically the lm561c of course. You see some with resistors, and some without. I'm guessing/gathering the resistors are for Constant Voltage drivers and the Constant Current are without resistors?
So those resistors are to protect the LEDs from overcurrent but also generate heat and decrease efficiency? (Power=Current^2*Resistance)
Are there safety issues to be concerned about if using the Constant Current ribbons that don't have resistors?
If someone accidentally uses a Constant Voltage driver on such a ribbon what would happen? I notice the boards coming out and the Samsung strips seem to be resistorless Constant Current but I think I've seen people using Constant Voltage drivers with some? I may be mistaken.
Re: LED Ribbons/Resistors/CV&CC
Posted: Wed Sep 20, 2017 3:04 am
by LEDG
Jimmy Jam wrote: ↑Wed Sep 20, 2017 2:23 am
Okay my first question is about LED ribbons, specifically the lm561c of course. You see some with resistors, and some without. I'm guessing/gathering the resistors are for Constant Voltage drivers and the Constant Current are without resistors?
So those resistors are to protect the LEDs from overcurrent but also generate heat and decrease efficiency? (Power=Current^2*Resistance)
Are there safety issues to be concerned about if using the Constant Current ribbons that don't have resistors?
If someone accidentally uses a Constant Voltage driver on such a ribbon what would happen? I notice the boards coming out and the Samsung strips seem to be resistorless Constant Current but I think I've seen people using Constant Voltage drivers with some? I may be mistaken.
More and more people are realizing that the gear we're dealing with works just fine without resistors. As soon as you wire a strip in parallel with another, you can throw the "constant current" element away, because the current is no longer regulated, really. Having experimented on COBs and boards, trying to get them to go into thermal runaway, I don't see a need for resistors in parallel/constant voltage setups. In my testing, it took quite a bit of current and heat to get things to go thermal.
Now, we're seeing lights like the PLC 6 being sold that are running multiple COBs HARD in parallel without issue. We're also seeing strip builds like the one Ted did that are being run completely in parallel on a CV driver, no problem.
Re: The Quick Question Thread
Posted: Sun Oct 01, 2017 4:23 am
by charsi
Helloze,
thanks for the forum! and here goes my quick question
I am in the process of getting some custom lm561c strips in 54 volts ( 6 led unit /3 in series)
I am getting the s6 A1 voltage bin (2.8-2.9v) the question is since the vf will be different at different currents will the hlg 240h 54 b work, b version has external dimming but no voltage adjustment pot like in the A, i want the b version so i can dim thru a pot and not have to fiddle around with the screw driver.
the reason getting custom strips in this configuration is tht i can have one driver that will be good for these and the cxm22 cobs so i can play around with different configs.
C
Re: The Quick Question Thread
Posted: Sun Oct 01, 2017 5:39 am
by LEDG
charsi wrote: ↑Sun Oct 01, 2017 4:23 am
Helloze,
thanks for the forum! and here goes my quick question
I am in the process of getting some custom lm561c strips in 54 volts ( 6 led unit /3 in series)
I am getting the s6 A1 voltage bin (2.8-2.9v) the question is since the vf will be different at different currents will the hlg 240h 54 b work, b version has external dimming but no voltage adjustment pot like in the A, i want the b version so i can dim thru a pot and not have to fiddle around with the screw driver.
the reason getting custom strips in this configuration is tht i can have one driver that will be good for these and the cxm22 cobs so i can play around with different configs.
C
Hello and welcome! Can you elaborate a little more on the layout of these strips? How many diodes are there total on each strip?
The B version will have exactly 54V output when the pot is turned all the way up. As you turn the pot down, it'll reduce the output current, thereby reducing the output voltage as well.
Re: The Quick Question Thread
Posted: Wed Oct 11, 2017 3:23 pm
by microgroaway
Hi Guys,
I am in the middle of getting parts together for a 10 strip (LT-H562D) powered with an HLG-185H-24A. My question is about terminal blocks and wire gauge.
1) Can I use 2 of these terminal blocks (one + and one -) to connect the driver to the strips? Or is there a better choice?Is it ok to connect one lead from the driver, and have 10 coming out?
https://www.arrow.com/en/products/17189 ... -contact
2) I picked that terminal block because it can handle up to 14AWG. So, is 14 needed? It seems like 16 would be more than enough and 14 is like overkilling the overkill.
Thanks guys.