Looking to build a full wave rectifier into a cheap string of LED lights

[Red_Chaos1]

I did a bit of searching and didn't see anything specifically about this, so please pardon me if it has in fact been covered, or if this is the wrong place to be posting.

The local HEB has 30 light strings of various colors for $4.99, so I figured I'd get 2 sets, knowing full well they'd likely have the 60Hz flicker going on. I am knowledgeable enough about electronics to recognize most components, and I know how to solder and have repaired numerous devices over time. However, I do not know how to build a full wave rectifier nor did I know that that was what I needed, among other things, to fix the flicker issue. I merely knew that more expensive strings could be purchased which handled the flicker. Seeing as I am bored and have been itching to work with electronics, I opted to buy the cheap strands and do the work.

I posted on another forum I frequent about this and got some info with some links, but nothing really concrete. Looking at posts here, it would seem there are much more knowledgeable folks afoot.

What I am hoping is that someone here would know with a fair level of certainty, what components I would need to buy, and how to hook them up to build the rectifier and such to bring the flicker up to a level I cannot see it.

The strings are typical for LED xmas lights I presume, non polarized plug, 3A fast acting fuse for each blade, then the wiring going into the cathode of an LED and out the anode into two 620 Ohm 5% resistors in series, and then out to the remaining 29 LEDs, cathode to anode all the way to the tip, then back along the other wire to the plug again.

Without a multimeter or something there isn't much more info I can provide at this point. I am hoping this is enough info to get some kind of an idea what would be safe to use to make these strands flicker free.

[budude]

Hey Red_Chaos1 - Welcome to DIYC! My suggestion is to go through Tony's excellent tutorial in the first post of THIS thread - it pretty much describes exactly what you want to do. As you are new to this, please be sure to post here if you have any questions - the most important thing is to be safe.

[Red_Chaos1]

Hey Red_Chaos1 - Welcome to DIYC! My suggestion is to go through Tony's excellent tutorial in the first post of THIS thread - it pretty much describes exactly what you want to do. As you are new to this, please be sure to post here if you have any questions - the most important thing is to be safe.

That *is* very close, but there are 2 things: My string is 2 wire only, not 3, and it only has one plug. They are not built for chaining. So I'm not sure how I would go about changing things to adapt.

And thanks for the welcome.

[Penfold]

Chaos have you tried to solder in a bridge rectifier like the 625-DF06MA-E3 you can get at mouser?

[holtm]

I bought some DF02M_Q bridge rectifiers from mouser, cut the power cord and soldered in the rectifer. The polarity is important. The LEDs are a little brighter and almost no flicker. I used hot glue to stabize the cords around the chip and covered it with heat shrink tubing.
I also have a mega tree with LEDs, I didn't want to do this for 48 strands, so I ordered a 15A bridge rectifier and mounted it in a single outlet box with a plug and duplex outlet. I then daisy chain all of the mega-tree SSRs and LEDs from it.

[Red_Chaos1]

Chaos have you tried to solder in a bridge rectifier like the 625-DF06MA-E3 you can get at mouser?

I'm guessing that could work, but I'd still need to know how to wire it in, and if I'd need any other parts to go with it, etc.

[dmcole]

Chaos have you tried to solder in a bridge rectifier like the 625-DF06MA-E3 you can get at mouser?

I'd think that particular device would be difficult to solder in-line into a light string.

My choice would be the W10G-E4/51, which has quite a bit longer leads, so there'd be more twisting-and-soldering room. There's a similar beast at Radio Shack (except that it costs almost precisely four times as much).

Bridge rectifiers have four leads -- two are marked with the tilde (~ -- it's the shift of the key just to the left of the !/1 key on your keyboard), one is marked plus (+) and one is marked minus (-).

I might build myself a little piece of reinforcement at this juncture. You could certainly use a piece of perf board (Radio Shack carries this but they also have some without the copper -- I just couldn't find it in my quick search), but I'm also thinking that a piece of narrow popsicle stick (about the width of the top of the rectifier) would work; you'd just drill four holes in in.

You want the rectifier to splay out with the two tilde leads going the the left and the plus/minus leads going to the right.

You cut the wires leading between the male plug and the first light in the LED string (there is usually a "pod" of resistors on the string just before the first light on the string; include the pod with the lights). Now you have four wires; connect the two wires coming from he male plug to the two rectifier leads marked with the tilde -- it doesn't matter which goes where. These should be soldered and covered with heat-shrink tubing so that none of the metal is exposed to the air (heat-shrink tubing requires placement before the joints are soldered -- push some onto the wires before twisting and soldering).

Now you have 120 volts -- pretty powerful stuff, so be careful with this next step -- of direct current coming out of the the two leads on the rectifier marked plus and minus. For your first string, temporarily solder the two wires coming from the LED end of the string to the plus and minus leads on your rectifier. Make sure you put some sort of temporary insulation between these two joints and that the plus and minus leads aren't touching.

Plug the plug into the wall current. If it doesn't go "poof," you've hit a good milestone; if it does, you probably should seek other counsel.

If the lights light, you're in business. Make note of which wire from the LED end of the string went to the plus and which went to the minus, disconnect the temporary joint, add a big piece of heat shrink that's enough to cover the rectifier and the reinforcement, add some to cover the plus and minus solder joints and put it all back together, sliding the big piece of tubing over the reinforcement and the rectifier and covering up the whole mess.

If the lights don't light, you need to reverse the polarity of the wires between the LED string and the plus and minus of the rectifier. Try it out, make note of the new wiring scheme and do the stuff with the heat-shrink tubing.

Repeat for each of your strings.

So, in conclusion, your bill of materials for each string is:

*One bridge rectifier (from Mouser or Radio Shack -- you probably want the WOG package, at least 125 volts and 1 amp).

*Four pieces of small (just bigger in diameter than the light-string wire) heat-shrink tubing.

*One big piece of heat-shrink tubing.

*Some sort of reinforcement -- a popsicle stick or a piece of perf board cut to size.

And plenty of time. Even at assembly-line pace, this is probably a 10-minute job per string.

Best of luck.

\dmc

[Red_Chaos1]

post

\dmc

This is perfect, thank you! I will likely go the Mouser (or Fry's Electronics, they have stuff like that at more reasonable prices) route, as I am all too familiar with how crappy Radio Shack is. After all, I once worked for them, before they partnered up with RCA and all that, becoming the Radio Shack section in the mega-conglomo-corp store. I saw the writing on the wall and left not long after.

Also, the strings I have have the "pod" of resistors after one LED, does that make a difference at all?

[dmcole]

Yeah, I hear you on RS -- I was a customer when it was Allied and sold only ham and high-end fidelity gear. Now if you ask them about a resistor they look at you as though you're an alien.

Also, the strings I have have the "pod" of resistors after one LED, does that make a difference at all?

So it's wired like this (ASCII art always horrible; dots represent wire):

Plug ... LED ... pod ... LED ... LED ... LED ... (etc) ...
Plug .................................................. ..............

If so, then it should be OK too.

\dmc

[Red_Chaos1]

Yeah, I hear you on RS -- I was a customer when it was Allied and sold only ham and high-end fidelity gear. Now if you ask them about a resistor they look at you as though you're an alien.



So it's wired like this (ASCII art always horrible; dots represent wire):

Plug ... LED ... pod ... LED ... LED ... LED ... (etc) ...
Plug .................................................. ..............

If so, then it should be OK too.

\dmc

lol, yeah, even when I worked there it was becoming a running joke "You've got questions, we've got blank stares." They were hiring people that were only good at pushing cell phones and directv and all that. AT my store we all had a decent knowledge of components, so when someone came in needing a x.xK ohm resistor or xxxx mF radial lead caps or what have you, we knew exactly where to go or point you. Even as an employee I loathed going into a mall RS, because all they did was point and then ignore you if you weren't a big ticket customer.

Anywho, yeah, your ASCII is accurate, and that is how things are set up. So I'll still be sticking the rectifier in before LED 1 then. All I gotta do is find out if Fry's has the rectifier, and if so tomorrow I shall have flicker free LED strings. :D