LED stabilised power supply

lw395 said:
You might want some RF filtering with that sort of module.
I've found Navtex to be easily interfered with.
Click to expand...

Yep, your right. I had a very brief try with a portable ssb reciever next to it and it seemed ok, but trying again with the onboard transciever and a little handheld scope, it is a noisy little bugg"r throwing noise back up thge 12v supply. . :eek: But a 100µF capaciter across the input seems to clean it up fine.

Ta
 
OK oh learned ones, I've just installed 5 eBay cheapies on the boat to replace filament bulbs, just did a straight swap, they all work, no detectable RF interference and cast a pleasant light, why would I need regulators or any similar added gubbins.
 
Using a linear regulator to regulate voltage to drive leds is a bit pointless because you are dumping power into the heatsink. Silly if you are trying to reduce power consumption. More efficient by a long margin is using a switching type power supply. Problem is having one of those at each led is asking for trouble because the manufacturers are trying to keep costs down so you end up with 20 or so potentially poor rf radiators around the boat, also the cost of each 'bulb' is increased.

the sensible solution is to calculate how much power you will need to drive all your led lights, add a margin and install a central, switching, rf shielded, power regulator in the switch panel and use that as a fixed 12v supply to drive all the led lights at a fixed voltage. Then cheap resistor regulated 'bulbs' can be used.

A 5 amp central lighting supply would probably drive most sub 40' boats led light requirements. 10 amps would be overkill i suspect.
 
Vara said:
, why would I need regulators or any similar added gubbins.
Click to expand...

Maybe not need but a reg like the ebay one will keep the light bright even with the batteries low, and quite possibly extend the lifespan. Seems to be varying experience with cheap unregulated ebay leds, some blowing, others lasting fine. You pays yer money..
 
nimbusgb said:
Using a linear regulator to regulate voltage to drive leds is a bit pointless because you are dumping power into the heatsink. Silly if you are trying to reduce power consumption. More efficient by a long margin is using a switching type...
Click to expand...

By changing to a linear regulated LED system, you will have achieved something like an 85% power saving against incandescent bulbs.
By using an external switch mode converter you will only increase that saving by a few per cent.
That few percent may be negligible cost and effort or it may turn into a bit of a palaver with RFI.
Most people could better spend and cost and effort on making their fridge more efficient or improving the charging system, if the goal is getting the most out of the batteries.

A lot of the switchers only give the advertised efficiency at highish loads, the difference may be less than you think.
If you want the ultimate in efficiency, you need to look at purpose designed current mode LED drivers, these will outperform a switcher driving 12V leds.

Like many things, a certain level of improvement is easy and worthwhile, you can do better still, but it's a personal judgment how far into diminishing returns you wish to go.
 
nimbusgb said:
Using a linear regulator to regulate voltage to drive leds is a bit pointless because you are dumping power into the heatsink. Silly if you are trying to reduce power consumption. More efficient by a long margin is using a switching type power supply. Problem is having one of those at each led is asking for trouble because the manufacturers are trying to keep costs down so you end up with 20 or so potentially poor rf radiators around the boat, also the cost of each 'bulb' is increased.

the sensible solution is to calculate how much power you will need to drive all your led lights, add a margin and install a central, switching, rf shielded, power regulator in the switch panel and use that as a fixed 12v supply to drive all the led lights at a fixed voltage. Then cheap resistor regulated 'bulbs' can be used.

A 5 amp central lighting supply would probably drive most sub 40' boats led light requirements. 10 amps would be overkill i suspect.
Click to expand...

We're going round in circles - that was what I suggested in post #1 of this thread :rolleyes:
 
Hoolie said:
We're going round in circles - that was what I suggested in post #1 of this thread :rolleyes:
Click to expand...

It's a valid idea, but not the only way of doing things.
Good luck with the RFI.
BTW are you going to leave your central switching supply running all night in case you need to switch a light on?
I suspect that may make a mockery of the improved efficiency over a linear reg.
 
lw395 said:
It's a valid idea, but not the only way of doing things.
Good luck with the RFI.
BTW are you going to leave your central switching supply running all night in case you need to switch a light on?
I suspect that may make a mockery of the improved efficiency over a linear reg.
Click to expand...
As I said in post #38, following earlier discussions I've decided not to fit a stabilised supply and just buy a few extra spare LEDs. But I certainly take your point about a regulator using power when lights are off.
 
lw395 said:
BTW are you going to leave your central switching supply running all night in case you need to switch a light on?
I suspect that may make a mockery of the improved efficiency over a linear reg.
Click to expand...

Just measured the one from the ebay link. Flipping between 10 & 20mA with no load.
 
nimbusgb said:
Gee that'll drain my house batteries in ........... oh about 15000 hours.
Click to expand...

Indeed.
As I said, the extra efficiency of a switched DC-DC converter against a linear one is a negligible benefit at best.
A lot of switch mode converters have a bigger standing current though.
I've also had issues with them being noisier when very lightly loaded, although that was not in a boaty context.
 
You must log in or register to reply here.

Share this page

Top