DIY Outdoor LED
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So I deployed 5 more of these yesterday, so I have a total of 6 on the chain now.
The total current draw is ~5A at 12V...not bad!
Though I have an issue where the lights will go off for a little bit and then come back on.
Almost all of them are doing this and it doesnt happen at the same time so its not that the power is interrupted.
Makes me think as if the LED is heating up and shutting down and then when it cools down after a bit, it comes back on.
I tested them prior to deployment to make sure that they worked but didnt run them long enough that they would heat up. Plan on putting up one on the bench and leave it on longer to see if it does that.
But overall, not bad landscape light for 10 bucks!
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Update: The landscape light are programmed to come on in the evening and they did not turn on this evening. Further investigation yielded this:
The FET was touching the plastic case and melted it :-(
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@activemind are you dimming the led or only switch it? A (swich) fet in full saturation should have an internal resistance of less than 0.1 ohm. It would be hard to get it heated that much with a current in the range of 1 amp..
It could well be that your fet is not in full saturation. Take a look at the data sheet.. -
@mfalkvidd said:
This might help a bit http://www.aliexpress.com/item/10pcs-Free-Shipping-Aluminium-TO-220-Heatsink-TO-220-Heat-Sink-Transistor-Radiator-TO220-Cooler-Cooling/32684240364.html
Yup! I have them on order from China. Will try but I think I need to perforate the box too. Its drwaing ~5A which is amlost 60W. Maybe a little too much for a totally closed box!
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@activemind are you dimming the led or only switch it? A (swich) fet in full saturation should have an internal resistance of less than 0.1 ohm. It would be hard to get it heated that much with a current in the range of 1 amp..
It could well be that your fet is not in full saturation. Take a look at the data sheet..@AWI said:
@activemind are you dimming the led or only switch it? A (swich) fet in full saturation should have an internal resistance of less than 0.1 ohm. It would be hard to get it heated that much with a current in the range of 1 amp..
It could well be that your fet is not in full saturation. Take a look at the data sheet..I am dimming as well as turning them on/off. There are 6 such lights on this FET and when all are on, the draw is around 5A. I am guessing thats a little too much for this tiny heatsink in an enclosed box. Need to change the heatsink and perforate the box.
Thanks for the datasheet reminder. Let me go back and check whats the power I am dissipating when dimming these lights.
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@mfalkvidd said:
This might help a bit http://www.aliexpress.com/item/10pcs-Free-Shipping-Aluminium-TO-220-Heatsink-TO-220-Heat-Sink-Transistor-Radiator-TO220-Cooler-Cooling/32684240364.html
Yup! I have them on order from China. Will try but I think I need to perforate the box too. Its drwaing ~5A which is amlost 60W. Maybe a little too much for a totally closed box!
-AM
Yup! I have them on order from China. Will try but I think I need to perforate the box too. Its drwaing ~5A which is amlost 60W. Maybe a little too much for a totally closed box!
Most of the power will be dissipated in the lights. The power dissipated in the FET is the FET's resistance * current^2. If you are using a IRLZ44N FET I think that means 0.025 * 5^2 = 0.625W if you give the FET a signal of 5V. (0.025 ohm is the Static Drain-to-Source On-Resistance from the datasheet)
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Yup! I have them on order from China. Will try but I think I need to perforate the box too. Its drwaing ~5A which is amlost 60W. Maybe a little too much for a totally closed box!
Most of the power will be dissipated in the lights. The power dissipated in the FET is the FET's resistance * current^2. If you are using a IRLZ44N FET I think that means 0.025 * 5^2 = 0.625W if you give the FET a signal of 5V. (0.025 ohm is the Static Drain-to-Source On-Resistance from the datasheet)
@mfalkvidd said:
Yup! I have them on order from China. Will try but I think I need to perforate the box too. Its drwaing ~5A which is amlost 60W. Maybe a little too much for a totally closed box!
Most of the power will be dissipated in the lights. The power dissipated in the FET is the FET's resistance * current^2. If you are using a IRLZ44N FET I think that means 0.025 * 5^2 = 0.625W if you give the FET a signal of 5V. (0.025 ohm is the Static Drain-to-Source On-Resistance from the datasheet)
Heat dissapation in the lights is another issue I need to look into because with this new batch I ordered, they have been turning off after like 5 mins and then come back on by themselves. I think the heat sink on this new batch is not that good because the last batch did not do this.
I am using them at 12V so the power would be ~4W. Not too much but still enough to get the sink hot!
-AM
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@mfalkvidd said:
Yup! I have them on order from China. Will try but I think I need to perforate the box too. Its drwaing ~5A which is amlost 60W. Maybe a little too much for a totally closed box!
Most of the power will be dissipated in the lights. The power dissipated in the FET is the FET's resistance * current^2. If you are using a IRLZ44N FET I think that means 0.025 * 5^2 = 0.625W if you give the FET a signal of 5V. (0.025 ohm is the Static Drain-to-Source On-Resistance from the datasheet)
Heat dissapation in the lights is another issue I need to look into because with this new batch I ordered, they have been turning off after like 5 mins and then come back on by themselves. I think the heat sink on this new batch is not that good because the last batch did not do this.
I am using them at 12V so the power would be ~4W. Not too much but still enough to get the sink hot!
-AM
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I am using them at 12V so the power would be ~4W. Not too much but still enough to get the sink hot!
The voltage makes no difference. 5A is still 5A.
@mfalkvidd said:
I am using them at 12V so the power would be ~4W. Not too much but still enough to get the sink hot!
The voltage makes no difference. 5A is still 5A.
you are right :-) brain fart
