Quote Originally Posted by Doddy View Post
14 parallel LEDs? without independent current limiting resistors?, that's a crap design - the drive circuit will - as you say - be designed to drive the power of each LED, but any variance (and they'll be plenty) in the characteristics (forward-volt drop) will see that particular LED consume more power and fail sooner - and, as identified - that results in a cascade of subsequent LED failures.

Designed to fail.
And somebody will have been paid to design that!

In practice LEDs are best supplied with a constant current supply rather than constant voltage as the forward voltage of the devices is very temperature dependant. I think most commercial units have a simple chopped AC drive circuit which is unidirectional but pulsed. A propper constant current DC supply will give a stable light output and greater reliability. You can also dim them very easily over a wide range. I designed and made a set of hight stability, dimmable LED stage lights for my former animation studio a few years back. The drive circuit isn't expensive to build and is fed from a standard Chinese switch-mode PSU. I can probably find (or redraw) the circuit if anyone is interested.