Homemade AC LED Driver Design

[andersonEE]

Hey, do any of you make your own AC drivers for your Fixed Lighting LED projects? I've been looking at this site for months now and their design examples are very detailed and even give pcb layouts and parts lists. The two that I have been looking at trying are both 12V, 350ma constant current drivers. One is isolated, the other is not. They do have higher power designs but I'd like to start small.

Maybe this thread can be a "Post your AC driver design" thread. Doesn't have to be your design, just show what you used.

 

[Steve K]

There's an OnSemi part that I thought would be useful for home projects, the NCP1216.
http://www.onsemi.com/PowerSolutions/product.do?id=NCP1216A

They have a design note describing it being used as a 500mA led driver, DN06050:
http://www.onsemi.com/pub_link/Collateral/DN06050-D.PDF

Seemed like it would be easy to adapt to different applications.

regards,
Steve K.

 

[kethd]

Non-isolated drivers raise very interesting safety questions about "electrically isolated" LED bases. If the heat sink is exposed to potential user contact (which it often would be to maximize heat dissipation) I would hesitate to trust the built-in internal LED isolation to protect from shock.

 

[Steve K]

Good point about safety. What is the standard practice? Short of adding a GCFI, my thoughts are to tie the housing/heatsink/etc. to safety ground, and add a fuse in the power wire. If AC mains power ever contacts the housing/heatsink/etc., the fuse should blow and the user should be safe.

I believe that this was standard practice for electric tools, etc., back 20 or 30 years ago. More recent practice for these tools has been to just use plastic housings to avoid any opportunity to shock the user. I'm not sure how well that will work out for lights!

regards,
Steve K.

 

[andersonEE]

I agree Steve. Ground the heatsink, use a fuse and it should be pretty safe.