Thursday 17 January 2019

LED COB Chip 220V 20W Review

After spotting this on EBay I just had to have a play with it. LED driven directly from my 240Vac 50Hz Power Supply (standard 1Ph distribution voltage supplied to NZ homes). So I went ahead and bought 3 of the 20W variety!


Wiring seemed pretty straight forward, just solder the appropriate rated cable to these welding points as shown in the above image, apply voltage and lets see what happens.

Well actually no, I had a some concerns:-

- that's 240V mains voltage on exposed terminals
- 20W on something so thin ? I need find some way to dissipate heat.

Solve the Problem No2 First: Heat Dissipation.

Working with computers I get access to a lot of bits and pieces and I knew 1 day I'll find a use for all those Pentium 4 heatsinks. Drill 2 holes, screw the COB to the heatsink, and I didn't even use thermal paste. Solder on some wires from a discarded appliance cable, plug it in a wall socket and let it run for about an hour.

Result: After removing the mains, did the "carefully feel the heatsink" method, happy to say the heatsink felt only slightly warm. At this point I should mention Do Not Look Directly at the COB when it is powered on.

Solving Problem No1: Exposed 240V Terminals.

Last year I have been replacing all the light fittings as shown above with LED fittings.

I now have a container to mount these 20W COBS safely.

Note the 3 screws (near the centre) screwed directly into the fins of the heatsink, this worked out quite well.

All 3 mounted onto the rafters out in the old shed.

Conclusion:
I'm really pleased how this small project worked out, especially re-purposing old light fittings I would normally have thrown away. I am in the process of buying more of these 20W COBs even though I cannot think of where they are to be used. As always the trick to doing this type of project comes down to appropriate case/fitting that adequately mounts for both COB and heatsink, with safe termination while still looking good.

Note, the heatsink was significantly warmer after a time when mounted inside the light fitting.

MyScore: 9/10

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