takao21203
- Joined Apr 28, 2012
- 3,702
I made a panel with small LEDs a few days ago.
I run this from a 12V electronic transformer (1A).
Voltage is 25 volts, since I run many LEDs in series.
There is some point where they heat up too much about at 26 volts. Not they would fail totally, but one string goes off after a while.
Using a MC34063 booster, I run them at 25.7 volts now for a few days, don't get that hot, nothing fails or burns out.
They do however if the voltage is too high.
The current limit is dimensioned so they won't just burn totally and pop useless. But, the actual current is below that.
These panels are not so much useful alone, since you really need 660nm red, the blue is not so important, but 445nm blue is better.
These LEDs are all 630nm.
1W LEDs are far more bright yes, or 3W LEDs.
Really interesting it become when using 10W, 20W, and 30W LEDs.
Don't expect too much from a 630nm panel, plants will start up, but then stretch later, don't flower, or much smaller flowers/fruits.
There should be more red than blue, at least 1:1. You normally should get a saturated, deep pink.
1 Ohms resistors will do nothing, for 20mA LEDs.
If you add a resistor, you increase the voltage margin, nothing else. It is a few volts if you consider turn on, and about 1V to 2V (depends how many LEDs) is the useful adjustment range.
Adding a resistor only will increase the range.
If the actual real current is correct, it can be caused by anything- totally irrelevant.
The tighter you pack the LEDs, the more heat, also the small plastic cases are not good heat conductors. If they are hot to touch, they are already sizzling inside. All what's allowed is them getting a little warm but not hot.
It takes half an hour or so to heat up fully for a panel, also room temp. will affect this.
So, unless you use costant current LED driver, you need to adjust your current well below the limit. Measuring is not so good, since it will show a lower current than real current.
Connecting to a voltage source is never really a good thing, if it is not current limited, it could deliver any current into your LEDs.
I drive with voltage only, but I also use an active current limitation. It is set the LEDs would turn very hot, but NOT burn out under any circumstances, not immediately.
Same for larger power LEDs, I have a transformer which when loaded with 300W or so, will produce a voltage which only will make the LEDs turn very hot, but not burn out or explode.
I do not recommend anything but to use ready-made LED drivers. Otherwise, you will end up with popped LEDs no matter what.
If you like, experiment, but don't say you saw the information on a forum you can just connect the LEDs without resistor. Of course you can. But you need a lot of experience to do it right. And even so, there are cases when you anyway would want to use a ready-made LED driver. For the one or the other reason.
The best is to load the power supply just adequately, not to use a large overdimensionated supply. Many electronic transformers also have an overcurrent limit.
So it would be quite hard to destroy your whole panel.
I have destroyed power LEDs, a few blue one's, and some red one's, which were crap anyway.
I run this from a 12V electronic transformer (1A).
Voltage is 25 volts, since I run many LEDs in series.
There is some point where they heat up too much about at 26 volts. Not they would fail totally, but one string goes off after a while.
Using a MC34063 booster, I run them at 25.7 volts now for a few days, don't get that hot, nothing fails or burns out.
They do however if the voltage is too high.
The current limit is dimensioned so they won't just burn totally and pop useless. But, the actual current is below that.
These panels are not so much useful alone, since you really need 660nm red, the blue is not so important, but 445nm blue is better.
These LEDs are all 630nm.
1W LEDs are far more bright yes, or 3W LEDs.
Really interesting it become when using 10W, 20W, and 30W LEDs.
Don't expect too much from a 630nm panel, plants will start up, but then stretch later, don't flower, or much smaller flowers/fruits.
There should be more red than blue, at least 1:1. You normally should get a saturated, deep pink.
1 Ohms resistors will do nothing, for 20mA LEDs.
If you add a resistor, you increase the voltage margin, nothing else. It is a few volts if you consider turn on, and about 1V to 2V (depends how many LEDs) is the useful adjustment range.
Adding a resistor only will increase the range.
If the actual real current is correct, it can be caused by anything- totally irrelevant.
The tighter you pack the LEDs, the more heat, also the small plastic cases are not good heat conductors. If they are hot to touch, they are already sizzling inside. All what's allowed is them getting a little warm but not hot.
It takes half an hour or so to heat up fully for a panel, also room temp. will affect this.
So, unless you use costant current LED driver, you need to adjust your current well below the limit. Measuring is not so good, since it will show a lower current than real current.
Connecting to a voltage source is never really a good thing, if it is not current limited, it could deliver any current into your LEDs.
I drive with voltage only, but I also use an active current limitation. It is set the LEDs would turn very hot, but NOT burn out under any circumstances, not immediately.
Same for larger power LEDs, I have a transformer which when loaded with 300W or so, will produce a voltage which only will make the LEDs turn very hot, but not burn out or explode.
I do not recommend anything but to use ready-made LED drivers. Otherwise, you will end up with popped LEDs no matter what.
If you like, experiment, but don't say you saw the information on a forum you can just connect the LEDs without resistor. Of course you can. But you need a lot of experience to do it right. And even so, there are cases when you anyway would want to use a ready-made LED driver. For the one or the other reason.
The best is to load the power supply just adequately, not to use a large overdimensionated supply. Many electronic transformers also have an overcurrent limit.
So it would be quite hard to destroy your whole panel.
I have destroyed power LEDs, a few blue one's, and some red one's, which were crap anyway.
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