Overcurrent protection techniques

Rocket Soul

Rocket Soul

Well-Known Member
7CardBud said:
Am I missing something here? Are you against fuses or are you motived to build some sort of LED Rube Goldberg machine?
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Who is Rube Goldberg? And what exactly is making you believe i have some bad animus to s certain type of electronic components?

Im not sure if im missing something here, all i am doing is showing op the solution to his problem is much easier than attaching fuses. Its hard to tell online but im getting a real passive aggressive vibe here but i also understand if you feel the same way, if so sorry :)

Youve not touched on my reply, does it make sense to youu?
 
cobshopgrow

cobshopgrow

Well-Known Member
KlompenOG said:
Thanks, I am still trying to learn the weird relationship between diodes and their power supply; they're not quite resistors, not capacitors, not transformers, and really not even completely like other semiconductor products. For such a simple device, the nuance of it can be surprisingly complicated. I know many strips/tape lights have resistors on them but the EB strips don't seem to, and honestly I haven't learned all this enough to know what all the consequences of that are.

Interestingly enough, I found a LCD display that shows voltage/wattage/amperage/etc that is wired in series with the circuit and allows you to set voltage/current cutoff levels. They also sell some that are wired in parallel and use a toroidal inductor as a sensor that you run one of your leads through, but those can't cut power. One of these days I'm going to set up an Arduino that just handles all of this crap in one device.
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LEDs arent soo complicated and i think you allready have a good understanding.
for us here we can prob simply see them as resistors, even theyre none.
every led is a little resistance for the driver causing a voltage drop, this is measured by the driver and thats what he is working/steering with.
this is maybe a bit oversimplified.

the EB strips dont use so called preresitors as theyre ment to be driven direct.
benefit of a preresitor is that it caps the current you can draw, drawback is he will always eat some current.
so not using preresitors is the prefered way, like the eb strips and other high power strip are setup.
basically you can put a small preresitor in series with your EB strips to get a fuse, but you need to calc that and see that the resitor can take it (there are online calculators).
its not a good way to do anyway, its good for signal leds, not for power leds.

its funny you mention this meters, many ppl here use these with good results and no problems at all.
while i have to say that i wired once such a meter in series (different type, RC volt/ampmeter, so ymcv) and had some strange behaviour when i quickly changed the intensity, the driver didnt like to drive this non LED device (in fact a complete electronic circuit with a own voltage regulation onboard).
only problem where the quick intensity changes, but after i saw that i simply dont use them anymore.
 
KlompenOG

KlompenOG

Active Member
cobshopgrow said:
LEDs arent soo complicated and i think you allready have a good understanding.
for us here we can prob simply see them as resistors, even theyre none.
every led is a little resistance for the driver causing a voltage drop, this is measured by the driver and thats what he is working/steering with.
this is maybe a bit oversimplified.

the EB strips dont use so called preresitors as theyre ment to be driven direct.
benefit of a preresitor is that it caps the current you can draw, drawback is he will always eat some current.
so not using preresitors is the prefered way, like the eb strips and other high power strip are setup.
basically you can put a small preresitor in series with your EB strips to get a fuse, but you need to calc that and see that the resitor can take it (there are online calculators).
its not a good way to do anyway, its good for signal leds, not for power leds.

its funny you mention this meters, many ppl here use these with good results and no problems at all.
while i have to say that i wired once such a meter in series (different type, RC volt/ampmeter, so ymcv) and had some strange behaviour when i quickly changed the intensity, the driver didnt like to drive this non LED device (in fact a complete electronic circuit with a own voltage regulation onboard).
only problem where the quick intensity changes, but after i saw that i simply dont use them anymore.
Click to expand...
I have been doing some studying and have learned about thermal runaway.... Do the Bridgelux strips lack internal protection against such? It seems like as long as I keep them cooled well it probably won't be a problem, but it would be good to be sure. I was thinking about adding a CC dimmer of some kind, but I don't know what type works best with my constant voltage driver(an Asus laptop adapter). Does PWM dimming work ok with these strips and driver?
 
cobshopgrow

cobshopgrow

Well-Known Member
the eb strips are just containing diodes, no protection, which would cause losses.
the protection of the strips is good factory matching, its in fact so good you can simply run them in parallel and it will work out fine.

the strips with the preresitors you refer to arent as good matched and they run on pretty unregulated power supplies often, therefore the resitors are in place.

as long youre in the special led driver world youre fine, your driver is your protection, A type driver you can cap the voltage, B driver works with fixed current anyway.

the eb strips are made to be driven in series by a constant current supply,so there wont be a way for a thermal runaway.
if you look around you will see that most of the generic led drivers are constant current, 350mA and 700mA are very popular f.e.
this the classic way recommended by manufactorers to drive a high power led, but plenty ways will work, parallel ,mix of, etc. quality strips are really well matched.

didnt 1212ham used some kind of external dimmer in his example? some kind of PWM signal switching a FET sold for these generic cheap led strips?
its prob not the most elegant way to do it, but its the easiest way to dimm your laptop driver.
See that the Ampere and Voltage rating is high enough, at 8A the Fet have to work a bit.

PWM dimming works absolute flawless with leds, that is no problem, as long you switch the drivers output he should be fine.
 
1

1212ham

Well-Known Member
KlompenOG said:
I have been doing some studying and have learned about thermal runaway.... Do the Bridgelux strips lack internal protection against such? It seems like as long as I keep them cooled well it probably won't be a problem, but it would be good to be sure. I was thinking about adding a CC dimmer of some kind, but I don't know what type works best with my constant voltage driver(an Asus laptop adapter). Does PWM dimming work ok with these strips and driver?
Click to expand...
People talk about thermal runaway but I've never seen a single case reported on RIU. As I understand it, grow lights don't drive the diodes hard enough to get close to thermal runaway. As for PWM, I gave you links. ;-)

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Rocket Soul

Rocket Soul

Well-Known Member
Id forget about thermal runaway. Youtube ledgardener quantumboard torture for a good laugh: he only had very low and marginal thermal runaway (thermal walkaway) even when running his 1 qb close to 600w. Did he break it? No spoilers, have a look....
 
KlompenOG

KlompenOG

Active Member
cobshopgrow said:
the eb strips are just containing diodes, no protection, which would cause losses.
the protection of the strips is good factory matching, its in fact so good you can simply run them in parallel and it will work out fine.

the strips with the preresitors you refer to arent as good matched and they run on pretty unregulated power supplies often, therefore the resitors are in place.

as long youre in the special led driver world youre fine, your driver is your protection, A type driver you can cap the voltage, B driver works with fixed current anyway.

the eb strips are made to be driven in series by a constant current supply,so there wont be a way for a thermal runaway.
if you look around you will see that most of the generic led drivers are constant current, 350mA and 700mA are very popular f.e.
this the classic way recommended by manufactorers to drive a high power led, but plenty ways will work, parallel ,mix of, etc. quality strips are really well matched.

didnt 1212ham used some kind of external dimmer in his example? some kind of PWM signal switching a FET sold for these generic cheap led strips?
its prob not the most elegant way to do it, but its the easiest way to dimm your laptop driver.
See that the Ampere and Voltage rating is high enough, at 8A the Fet have to work a bit.

PWM dimming works absolute flawless with leds, that is no problem, as long you switch the drivers output he should be fine.
Click to expand...
Thanks for the reply. I think that makes sense to me now. Seems like in some ways maybe I am thinking of this backward; What if instead I went for a driver that is just adequate for the load and no more? Seems like worst case scenario then would be that I overload the driver and the fuse pops. Better to replace one fuse than many after all..... At 350mA, ten of the strips would pull about 3.5A, and I have a few drivers in that range. I have mainly been looking at laptop drivers because I literally have dozens of them sitting around and money is a major obstacle right now. I desperately need to make sure our supply of medicine continues, but I also have to fight my partner on any spending because we're so damn poor. She'll smoke the stuff all day, but getting her interested in the slightest in actually growing it seems to be too hard. Makes it hard for her to relate to what I may need for it. It took weeks to get her to ok the QB96, and I still have a lot I want to add to the whole setup....
 
cobshopgrow

cobshopgrow

Well-Known Member
if i would had dozens of these drivers at hand i would also see to make them work.
it sounded to me theyre really usable.

"What if instead I went for a driver that is just adequate for the load and no more? "
youre basically going this way when you connect many many strips.

at 350mA you drive the strip very low (true for most strips were using here at least).
i would give it a try with the mentioned 10 strips, at 3.5A from the power supply,
not much bad should happen.
the problem with these powersupplies is that you dont exactly know what they can deliver.
it could be also 4A, or more, or less, the notebook driver will give what it can not exaclty 3.5A.
but you have plenty headroom as it sounds.

dont forget that any kind of driver will have protection mechanisms, fuses etc. inbuild.
 
KlompenOG

KlompenOG

Active Member
Wow that QB torture test was interesting. The diodes on the BXEB series are 2835 diodes, which are smaller than the LM561 chips by a little. I have no idea if Bridgelux diodes have at all comparable power handling, but its probably in the ballpark. They're one of the few high efficiency Asian LED strip makers that aren't using Samsung diodes.
 
Rocket Soul

Rocket Soul

Well-Known Member
KlompenOG said:
Wow that QB torture test was interesting. The diodes on the BXEB series are 2835 diodes, which are smaller than the LM561 chips by a little. I have no idea if Bridgelux diodes have at all comparable power handling, but its probably in the ballpark. They're one of the few high efficiency Asian LED strip makers that aren't using Samsung diodes.
Click to expand...
I wouldnt try it with strips. The test runs each diode at almost 2w with no probs. My mate accidentally ran a blux vesta strip (same diode) at 200w/1w per diode and it melted. Point is: no tthermal runaway, dont worry about it with same batch/model midpower diodes.
 
1

1212ham

Well-Known Member
KlompenOG said:
Thanks for the reply. I think that makes sense to me now. Seems like in some ways maybe I am thinking of this backward; What if instead I went for a driver that is just adequate for the load and no more? Seems like worst case scenario then would be that I overload the driver and the fuse pops. Better to replace one fuse than many after all..... At 350mA, ten of the strips would pull about 3.5A, and I have a few drivers in that range. I have mainly been looking at laptop drivers because I literally have dozens of them sitting around and money is a major obstacle right now. I desperately need to make sure our supply of medicine continues, but I also have to fight my partner on any spending because we're so damn poor. She'll smoke the stuff all day, but getting her interested in the slightest in actually growing it seems to be too hard. Makes it hard for her to relate to what I may need for it. It took weeks to get her to ok the QB96, and I still have a lot I want to add to the whole setup....
Click to expand...
"What if instead I went for a driver that is just adequate for the load and no more?"
The thing is that the load is a variable, the current draw (load) is dependent on the voltage applied, a Blux Gen 2 draws 750ma at 19.5v and 1400ma at 20.5v. As cobshopgrow mentioned, those power supplies have protection, they should shut down or throttle back if overloaded or overheated. The one I often use to power my RC charger (iCharger 206B) will throttle back if I exceed it's rated current.

Quality light doesn't get much cheaper than Blux Gen 2's, a dimmer and cheap or free power supplies.
I checked five 19.5 volt Dell supplies and voltage is between 19.12 and 19.47. My 20v Dell supply measures 19.99v and cost me $1.50 at a thrift store. :cool:

A 20v supply would be best but you should be good with a supply in the 20-24v range, a PWM dimmer and some type of meter to measure power.
Many have used the meters you linked or an AC power meter like the Kill-a-Watt.
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