LED driver, voltage smoothing

[s/v Jedi]

Originally Posted by GILow

Just reporting back.

Happy to say that did the job perfectly, thank you SV/Jedi. I found the same device on the Australian Ebay site (https://www.ebay.com.au/itm/XL6019-B...72.m2749.l2649) for AU$10 and it has worked a treat.

My only complaint is that I can no longer tell when the Webasto furnace is doing its shutdown procedure, which used to make the lights go crazy.

But I think I can live with that.

Great, glad you got that working. Funny how all the naysayers are absent now

[Wotname]

I am still following with interest so I guess I wasn't a naysayer .
Glad to hear you resolved the intermittent disco lighting Matt

[GILow]

Full disclosure, the little bugger runs hotter than I’d like. I’ll get the multimeter on at some stage and figure out how much power is being wasted, I’m guessing 5 watts or more.

But, that’s only while it is in operation. It’s cold in standby mode (power being fed to it, but all the downstream lighting switches off).

Real numbers to follow, once I’ve handed in the next three assignments.

[s/v Jedi]

Originally Posted by GILow

Full disclosure, the little bugger runs hotter than I’d like. I’ll get the multimeter on at some stage and figure out how much power is being wasted, I’m guessing 5 watts or more.

But, that’s only while it is in operation. It’s cold in standby mode (power being fed to it, but all the downstream lighting switches off).

Real numbers to follow, once I’ve handed in the next three assignments.

How much did you connect to it? Also, do you have a heatsink?

[GILow]

Originally Posted by s/v Jedi

How much did you connect to it? Also, do you have a heatsink?

Maximum was about 3.5 amps. Trying to figure out a way of attaching a heat sink... got any suggestions?

[s/v Jedi]

Originally Posted by GILow

Maximum was about 3.5 amps. Trying to figure out a way of attaching a heat sink... got any suggestions?

Yes I think that is too much current for the module. Try it with half the LEDs (I think I wrote to use two? Or does each do 3.5A?)

Mine came with small heatsinks for the MOSFETs iirc. The FETs are cooled by the PCB but for 4A need heat sinks. I would be interesting to see power input vs power output, but the heat generated does not represent efficiency... it’s just that it accumulates when there is not enough thermal conductance away from the MOSFET.

[Lake-Effect]

Originally Posted by s/v Jedi

Great, glad you got that working. Funny how all the naysayers are absent now

I was hoping to hear the root cause of the flickering. I know the usual LED strips with their repeated series arrangement of 3 LEDs and a resistor are sensitive to voltage, but I'd still want to know why the other loads could cause that much fluctuation to the voltage reaching the strips.

Just my OCD asserting itself.

To GiLow - You can buy little aluminum heatsinks that stick onto the IC. I am suspicious of the max ratings given for many of these mass-produced modules. It often seems like they've just cut & pasted from the main IC's spec sheet, without designing the board to run at the max. If you think it's running hot, maybe you should seek out the next bigger module.

[s/v Jedi]

Originally Posted by Lake-Effect

I was hoping to hear the root cause of the flickering. I know the usual LED strips with their repeated series arrangement of 3 LEDs and a resistor are sensitive to voltage, but I'd still want to know why the other loads could cause that much fluctuation to the voltage reaching the strips.

Just my OCD asserting itself.

To GiLow - You can buy little aluminum heatsinks that stick onto the IC. I am suspicious of the max ratings given for many of these mass-produced modules. It often seems like they've just cut & pasted from the main IC's spec sheet, without designing the board to run at the max. If you think it's running hot, maybe you should seek out the next bigger module.

Because of the current-driven model, a small change in voltage results in a big change in current. This is amplified by the LED power curve where a small change in current results in a big change in light output. In other words: it’s exponential.

Surprising that you get those heatsinks at one place and not another. It was clear they were just tossed in by my seller

The thing is that the next bigger module... like the $25 one I linked for 4A... is probably the same module with a heatsink rated for that load. The regulator is so popular that anything that mentions 4A is that one

[s/v Jedi]

not MOSFET but the regulator itself of-course. I’ve been working on another circuit that uses MOSFETs so I see them everywhere

[Lake-Effect]

Originally Posted by s/v Jedi

Because of the current-driven model, a small change in voltage results in a big change in current. This is amplified by the LED power curve where a small change in current results in a big change in light output. In other words: it’s exponential.

Understood... I would still want to quantify the voltage dips when the offending loads are run, if only to confirm that there wasn't an undersize panel feed or suspect connection somewhere.

[GILow]

Total current of all three strings is 3.5 amps.

Left it running with two of the three strings and the temperature is fine, so the simplest option is probably to buy one more.

[s/v Jedi]

Originally Posted by GILow

Total current of all three strings is 3.5 amps.

Left it running with two of the three strings and the temperature is fine, so the simplest option is probably to buy one more.

Yes that is the way. I always spread lights over two sources, two breakers etc. so that when a breaker pops there is still light. This is code for larger spaces and just smart to do anywhere

[Sternwake]

I found my lower rated buck/boost converters to be not very efficient, and quite loud in the RFI spectrum.

I add the heatsink to any exposed transistor. I've bought those that come with peel off backing self stick thermal adhesive , and have used superglue, and also have some arctic silver thermal epoxy I can use.

Do scrub the surface of the transistor with a q tip dipped in some rubbing alcohol first, to insure proper adhesion, especially on those will peel and stick adhesive.

[GILow]

Originally Posted by s/v Jedi

Yes that is the way. I always spread lights over two sources, two breakers etc. so that when a breaker pops there is still light. This is code for larger spaces and just smart to do anywhere

Actually, the cabin lights are spread over three circuits, forward, midship and aft, but the strip lights are all on the midship circuit.

Sod’s Law.

But the three way split is nice because I can turn off the lights ate either end of the boat when those ends are not in use. For instance, the aft section is only used when I have guests, so it stays dark all week.