# Does building an inexpensive bridge rectifier cheap flickering LED Christmas lights create safety concerns? [closed]

OK, I bit on Home Depot's door buster LED christmas lights... 150 LED lights for under $5 each. How could I resist? (Answer: By remembering that cheap LEDs flicker, AND that I'm sensitive to it. ) https://www.instyleled.co.uk/what-causes-led-flicker-and-how-can-i-stop-it-happening/ Seeing as how they were door-busters, they are also non-returnable. I'd like to figure out how to make them work. I've done some research, which has shown that it's possible to create a dc rectifier/transformer/ that will make the flickering stop. https://www.youtube.com/watch?v=mqRd3q7k9OU Now, I think I can do all of that (I love soldering that gives you that much room to screw up. BUT, I'd rather just pay$5 for a professional version that absolutely positively won't overheat and burn down my house. I can NOT find anything that's not built for uses like under-cabinet lighting or dimmers, and which have specific connectors for specific manufacturers. Does anyone know if anyone sells something like this, or if there are kits that are a little LESS DIY in nature? Thanks!

Only answer at DIY was the suggestion to go with a frequency doubler, rather than a rectifier... but trying to search for those seems to only dig up voltage doublers, rather than frequency. I assume I'm asking the wrong questions, so any guidance would be greatly appreciated.

EDIT: OK, so this appears to be THE question: IF I insert a bridge rectifier into the string of lights, per the youtube video, and keeping the original fuses in the original plug intact BEFORE the rectifier, is there an increased chance of fire from the DC current in the strand, or will the fuses protect the line?

(Just re-edited to update the title, too.)

## closed as too broad by Bence Kaulics, Daniel Grillo, Dmitry Grigoryev, uint128_t, Voltage SpikeDec 6 '16 at 23:16

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

• the only worthy solution is an SMPS. The reasons can fill up this page. namely surge current on start is huge and during operation is inverse to voltage ripple,.... performance vs stress factors. Ripple current at 100/120Hz demands High value C for low ESR LED string etc.. – Sunnyskyguy EE75 Dec 7 '16 at 20:07
• Pretend I'm an idiot... actually, KNOW that I'm an idiot, and that I have NO idea what you just said there. Googling switched-mode power suplis (hoping that's what SMPS stands for), saw discussions of voltage ripple while researching bridge rectifiers... beyond that, totally afloat. I assume its really helpful info, though. Just a bit above (and to the left) of my helmet. – Dustin Kreidler Dec 7 '16 at 21:11
• What made you think you could make it work? No spec, no analysis of what string size or input power or weblink ? This needs too many assumptions to guess what you have and what will work. – Sunnyskyguy EE75 Dec 8 '16 at 2:17

I haven't tested it yet with LED Christmas lights, so I can't say it works, but in theory a bridge rectifier and capacitor should provide cleaner power for LEDs than AC or just a rectified wave. Any Daisy chaining would have to be with LEDs only. Not sure if this would be to wiring codes. Use at your own risk.

• Did you calculate the peak charge current on start at peak voltage? or the value of the Y cap needed for 10% ripple might be C>= 8* 1 /(120Hz*(ESR)) with ESR~150*15ohm so C>=30uF@350V without out a surge limiter the cap will charge up from zero crossing up to 120V in a 1/4 of a half cycle or ~2ms so Ic=20uF * 120V/2ms= 1.2Amp. If turned on at peak voltage 120Vac*1.414= 137Vp with an ESR of say 1 ohm for the cap and 1 ohm for the diode bridge peak current would be ~70 amps !! – Sunnyskyguy EE75 Dec 7 '16 at 20:26

I think you will find that a full wave bridge rectifier (and nothing else) will greatly reduce the visual flicker by effectively doubling the flicker rate. I did not watch the video you linked. It should work when connected with one polarity and not the other.

A suitable device would be a W04, good for 100W of lights on 120VAC.

However you will not likely find a commercial device that has a plug on one end and a receptacle on the other- such a device would be very dangerous since anything could be plugged into it, and many such combinations would result in damage or danger.

• I have the same problem and have thought many times to make a 230 Vac -> TOPswitch/Viper -> 230 Vdc converter with plug -> receptable out from a discarded dimmer or remote controlled switch as a universal solution to flickering Christmas ornaments. – winny Dec 5 '16 at 20:32
• Hm. Hadn't thought about the likelihood of blowing something else up by accident. Just because I know what the storebought or home-jury-rigged device is for, doesn't mean anyone else would know not to use it for anything else! – Dustin Kreidler Dec 5 '16 at 20:39
• @spehro which W04 did you have in mind? spec? – Sunnyskyguy EE75 Dec 7 '16 at 20:32
• @TonyStewart.EEsince'75 The W04 seems to be on its way out, but Allied still has them alliedelec.com/hvca-w04g/70016040/…. The 25/28 mm leads are nice for hand wiring. Or about US6.50 for 100 pieces W06 (higher PIV) from China, shipped. – Spehro Pefhany Dec 7 '16 at 20:45
• aha 50A surge rated, it might work with an 2A ICL and 50uF 400V cap here – Sunnyskyguy EE75 Dec 7 '16 at 20:52