Make your own LED light bulb

Well, not exactly “make” more “re-fit” a failed cheap Chinese LED light. I’ve bought a fair few different ones on AliExpress over the last 18 months or so and, to be honest, haven’t been impressed by any of them. Everything is done cheaply and they don’t last any longer than cheap tungsten bulbs as a result. Typically, you have a metal film capacitor on the input, a full- or half-bridge rectifier, a “just about in spec” electrolytic capacitor on the output, a couple of resistors and then far too many SMD LEDs wired in series.

These particular large globe style bulbs have about 45 LEDs in series. That’s just asking for trouble as there’s no way they’re all identical in terms of the current they draw. Inevitably, one burns itself out and the whole thing is then landfill. Ok, they’re cheap, but there’s a reason for that.

The latest "failed" LED bub

The latest “failed” LED bulb

Above you can see the latest “fail” – the ringed LED is actually closed-circuit so that isn’t, whilst it’s a problem, the reason for the “no-worky” behaviour. I couldn’t be bothered doing any more testing so didn’t go on to identify the culprit LED.

Also in the picture are a few bits I’ve acquired – 5 x 1W LED beads, 5 boards to fit them on, 5 x AMC7135 350mA constant sink current regulators and the insides of a readily available Samsung wall-wart. My plan was to use the new components to build an LED bulb that should last for a long time (well, a very, very long time I would hope).

So, let’s make a start…

Mount LEDs, solder wires to "wall wart"

Mount LEDs, solder wires to “wall wart”

Mount the LEDs on the flat side of the board…

5 x 1W LEDs

5 x 1W LEDs

They’re just stuck on with hot glue – what can possibly go wrong 🙂 ?

Next, put the constant current drivers on the other side…

Add some regulation

Add some regulation

And then the guts of the wall wart

240Vac to 5Vdc

240Vac to 5Vdc

Pop in the housing…

Cram it all in...

Cram it all in…

Put the cover on to make it look just like it did before

Oh, look! A cheap Chinese LED bulb...

Oh, look! A cheap Chinese LED bulb…

Test:

Back in the garage

Back in the garage

The new bulb is the closest one. It’s “proper” white rather than any of that lame “warm white” – I don’t care if I have harsh lighting in the garage, I just want to see.

It’s probably not quite as bright as the “original” but it seems bright enough – haven’t checked it out in the dark yet but I’m sure it will be fine.

There’s a fair bit of work involved in doing this but if you cobbled together a fairly basic circuit board then you could eliminate most of the wiring and the LED boards. You’d also be able to conduct heat away from the LEDs properly – although a 30 minute test didn’t show any apparent heat issues.

All in, I’m pleased with that and I’ll replace the others with this alternative LED bulb when they fail.

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