Commercial LED driver for for Flicker-Free String Lights - Page 1
Forum section: electronics / projects

author: Infrared_Fred
author_rank: Regular Contributor
timestamp: December 05, 2022, 11:39:31 pm
content: Hello fellow Christmas light lovers!I have a bunch of the "base trim level" typical LED string lights that I use every year that are the usual config of LEDs in n*25 sets in series-parallel. (as in 25 leds in series prob with a current liming resistor wired across the 120V line, with multiple 25 led circuits in parallel for 50 & 100 light strings). they are nicelooking and all, but I don't care for the way they flicker at 60Hz due to the lack of a filter. I know there are lights available with rectifiers and filters (e.g. Ace Hardware has their store brand "celebrations" with regular, "gold" and "Platinum"; and they expressly say that they are full wave rectified (full wave for the plaitnum making them 5x bright than regular, and half-wave for the "gold" for 2x brighter, but anyway), but it would be too expensive to go through and replace all those strings just to get ones with rectifiers, not to metnion the fact that the strings I have work fine as is. I know LED powersupply/drivers exist for installation in commercial light fixtures, but I was wondering if one like this would work for driving the LED christmas lights if set correctly for the proper current level for the number of LEDs attached via the linear dimming feature. Here is the link to what I was thinkingELG-75-C500B;$35@digikey. According to the datsheet it is 10%-100% dimmable with linear current control, and can even come with a built in pot for easy setting; and is IP67 for outdoor use.If there is anything different under or around $50 that anyone can think of, I am open to suggestions on ways to eliminate the flicker safely? Do you think this would work?ThankS so much and Mery Christmas!

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: December 06, 2022, 12:06:21 am
content: These often have LEDs wired alternately in reverse-parallel so they can do various effects by switching polarity.In this case, the only way to reduce flicker is to either supply smooth DC, in which case only half the LEDs will light, or supply AC at a higher frequency

author: ajb
author_rank: Super Contributor
timestamp: December 06, 2022, 05:27:19 pm
content: Quote from: mikeselectricstuff on December 06, 2022, 12:06:21 amMost of the strings I see here that are direct-plug-in-to-mains style like the OP describes really are just long series strings. The ones that have various patterns are usually shorter series strings up to around 30V, or down to single LEDs in antiparallel.That LED driver will probably work if set to the right current range, and if wired to the LEDs correctly. You'll need tomake sure that the series strings are all connected correctly--they might not all be oriented the same way in the factory assembly. The current limiting resistor(s) in the string will reduce the driver headroom at higher currents, remember that the string was designed to provide reasonable average current to the LEDs with a peak voltage of ~170V. Since you'd be running them from DC you can set the actual average current you want which will be lower than that peak current by some amount. If your LED strings have a single resistor on each string molded into the wire then you could remove it, but some strings have individual resistors in some/all of the LED housings which would be a ridiculous amount of labor to remove--may as well buy the fancy new strings at that point! So in your position I would probably get a single driver and try it to make sure you can get reasonable performance before committing to a bunch of them.