Homemade LED anchor light circuit

[GHA]

Almost all of the lumen ratings you will see are for LEDs are for the the bare LED unit in perfect lab test conditions, not as it will be when fitted to a base and badly driven, usually giving a loss of around 30-40% of the base spec.

So which bad drivers should you look out for then? The circuit in the first post seems to push out a clean stable current, Is there something amiss?

There are purpose made simple IC's for driving LEDs, a common one is the PT4115, http://www.datasheetdir.com/PT4115+LED-Drivers which appears quite often in the cheap Ebay/Chinese driver boards and doesn't require many other components if you fancy building your own driver circuit, and supports dimming if you need it.

Definitely an option but is it really worth it? That seems to be a surface mount chip, maybe a bit beyond many.
Maybe a bit more efficient than an analog circuit but it's such low power there's not a lot in it.


ta

 

[DinghyMan]

So which bad drivers should you look out for then? The circuit in the first post seems to push out a clean stable current, Is there something amiss?



Definitely an option but is it really worth it? That seems to be a surface mount chip, maybe a bit beyond many.
Maybe a bit more efficient than an analog circuit but it's such low power there's not a lot in it.


ta

I usually find the bad drivers after I have bought them when I am testing them; overheating, interference, unstable output, under-rated components, etc.

Yes they are surface mount so fiddly but also available at sensible prices ready built: e.g. http://www.ebay.co.uk/itm/301123741210 complete with a 10w LED or http://www.ebay.co.uk/itm/12V-24V-1...-for-10W-High-Power-LED-UK-Stock/281194172454

Worth it? Depends on exactly what you are using them for and how long you want them to last. As lw395 says above there are many ways to do this and also there are many off the shelf boards that will do everything for you.

 

[GHA]

I usually find the bad drivers after I have bought them when I am testing them; overheating, interference, unstable output, under-rated components, etc.

Yes they are surface mount so fiddly but also available at sensible prices ready built: e.g. http://www.ebay.co.uk/itm/301123741210 complete with a 10w LED or http://www.ebay.co.uk/itm/12V-24V-1...-for-10W-High-Power-LED-UK-Stock/281194172454

Worth it? Depends on exactly what you are using them for and how long you want them to last. As lw395 says above there are many ways to do this and also there are many off the shelf boards that will do everything for you.

I was thinking more of is it worth it going for switch mode when for less than a quid you can make a linear one. Though for the price difference it's maybe not worth the bother. Saying that finding one with adjustable current limiting costs a bit more. And fitting the circuit into an anchor light size might not be so easy.

I've a load of buck, boost and buck boost about the boat from eBay some with both voltage and current regulation, great you can get so much so, cheap but they can be a bit RF noisy, a capacitor on the in and out has sorted any probs out so far.

A birthday treat ordered after some wine arrived from China yesterday
http://www.ebay.co.uk/itm/321553847015?_trksid=p2059210.m2749.l2649&ssPageName=STRK:MEBIDX:IT
Now can charge any lithium ions nice and gently

 

[DinghyMan]

I like the PT4115 solution as I drive the dimming pin to give multiple modes, buts that because I use them in torches and lights which need the option for dimming and want to drive the dimming at high enough rates to prevent any strobing effects with cameras.

If I wasn't interested in playing and learning I'd just go for the simplest circuit or more likely just order more bits from China and build one from them. At the moment I'm spending lots of time learning so am happy to build from components and adapt stuff even though its cheaper to buy ready made.

Just got a nice little logic analyser today for under a tenner plus delivery from a UK seller: http://www.amazon.co.uk/gp/product/B00DAYAREW now if only someone would do a 7" or 8" 100MHz Oscilloscope for £25 I'd be setup.

 

[lw395]

I usually find the bad drivers after I have bought them when I am testing them; overheating, interference, unstable output, under-rated components, etc.

Yes they are surface mount so fiddly but also available at sensible prices ready built: e.g. http://www.ebay.co.uk/itm/301123741210 complete with a 10w LED or http://www.ebay.co.uk/itm/12V-24V-1...-for-10W-High-Power-LED-UK-Stock/281194172454

Worth it? Depends on exactly what you are using them for and how long you want them to last. As lw395 says above there are many ways to do this and also there are many off the shelf boards that will do everything for you.

Thanks for the link.
10W LED for £2 bound to be useful....I'm thinking about deck lights under the spreaders. Probably want dimming for that.

I have one of my motorbikes in bits at the moment, I'd like some LED driving lights.
Also need some outdoor lights at home....