Electrical Engineer Question

"Rusty Vandura - www.tinyurl.com/keepoppo" (rustyvandura)
02/09/2016 at 19:05 • Filed to: None

I have a string of LED lights. 50 bulbs in the string. 3 wires. Along the string, in 3 or 4 places, are these things that resemble bulb sockets, but are plugged solid. Can you tell me what they are? Resistors, perhaps?

What I want is to shorten the string of lights to fewer than 10 bulbs, but I have no idea what would be required, as I am assuming that each bulb isn’t using 120 VAC.

Thoughts?

DISCUSSION (20)

bob and john > Rusty Vandura - www.tinyurl.com/keepoppo
02/09/2016 at 19:09

are there any markings on them at all?

Liam Farrell > Rusty Vandura - www.tinyurl.com/keepoppo
02/09/2016 at 19:10

It looks like you can open them? What's inside.

Zip-McBump > Rusty Vandura - www.tinyurl.com/keepoppo
02/09/2016 at 19:12

Kinda thought they were fuses.

Disclaimer: I’m obviously not an EE.

Phyrxes once again has a wagon! > Rusty Vandura - www.tinyurl.com/keepoppo
02/09/2016 at 19:21

Not an EE but....

Most holiday lights are wired in parallel so that if you lose one they all don’t go out, meaning each one gets full voltage from the power supply. Is there some sort of transformer in line with the power cord or is it built into the housing of the plug itself.

Those could be inline fuses but I’m not about to dig my lights out to look.

Why are you looking to shorten a strand? It might be easier to “build” a strand from scratch from off the shelf parts.

1111111111111111111111 > Rusty Vandura - www.tinyurl.com/keepoppo
02/09/2016 at 19:54

Your string is likely 3 or more strings. Then bridge rectifiers to make DC for each subsection. That’s my guess.

deekster_caddy > Rusty Vandura - www.tinyurl.com/keepoppo
02/09/2016 at 19:54

I would guess they are AC-DC transformers for the LED bulbs to run off. Do they throw off some heat?

edit - if you take one of the bulbs out is it possible to get the probes from a small voltmeter in there and see if the bulbs are being fed AC or DC current?

Rusty Vandura - www.tinyurl.com/keepoppo > deekster_caddy
02/09/2016 at 20:07

Good idea; I’ll try that.

Rusty Vandura - www.tinyurl.com/keepoppo > Phyrxes once again has a wagon!
02/09/2016 at 20:08

Could you school me in where to begin with that?

Rusty Vandura - www.tinyurl.com/keepoppo > 1111111111111111111111
02/09/2016 at 20:10

There are two wires at the plug, then three after the first light. And there are probably only three of those stubby things.

Rusty Vandura - www.tinyurl.com/keepoppo > bob and john
02/09/2016 at 20:10

None that I’ve noticed; I’ll take a closer look.

Rusty Vandura - www.tinyurl.com/keepoppo > Liam Farrell
02/09/2016 at 20:11

Haven’t tried. I sort of thought some Opponaut would say, “Yeah, those are fratastats.”

Rusty Vandura - www.tinyurl.com/keepoppo > Zip-McBump
02/09/2016 at 20:11

Mea culpa: I’m not either.

1111111111111111111111 > Rusty Vandura - www.tinyurl.com/keepoppo
02/09/2016 at 20:23

Then I’m going resistors. If you take out any of the bulbs you’ll have to account for more power being available to the remaining ones.

tromoly > deekster_caddy
02/09/2016 at 20:25

That’s my guess, some circuitry to both convert the voltage to DC and step down the voltage to something that won’t destroy the LEDs.

Rusty Vandura - www.tinyurl.com/keepoppo > 1111111111111111111111
02/09/2016 at 20:28

I want to light something made of glass from within using LEDs. I realize that they have particular power requirements, that they throw very little heat, and that they are small. Do you know how I might buy some LEDs and get them to light up? I can use a wall wart to provide DC power, but I wouldn’t know where to begin finding the information to know how many of what wattage to string together, what fratastats are required to be in line, or any of that. The string of lights I showed in my original post was one of about two dozen strings that I bought for $0.39 apiece at Walmart after Christmas. I thought I might just cut up one of those.

1111111111111111111111 > Rusty Vandura - www.tinyurl.com/keepoppo
02/09/2016 at 20:35

I got some of these recently and soldered on battery packs. Cost about 20$. And 2aa last forever.

https://www.amazon.com/gp/aw/d/B00LHQ…

You can tell a Finn but you can't tell him much > Rusty Vandura - www.tinyurl.com/keepoppo
02/09/2016 at 20:59

They are obviously too small to be turbo-encabulators, so you may be on the right track.

Phyrxes once again has a wagon! > Rusty Vandura - www.tinyurl.com/keepoppo
02/09/2016 at 21:44

Last time I did any serious tinkering with LEDS I used the single color strip from these guys: https://www.superbrightleds.com/cat/top-emitti…

You can cut the strip to the length you want and either use their solderless clip on leads or solder the the leads yourself. They do run off 12 volts so either arrange your batteries appropriately or use a 12v power supply that meets the specficiations (which they also sell).

Rusty Vandura - www.tinyurl.com/keepoppo > You can tell a Finn but you can't tell him much
02/09/2016 at 22:22

If they were, I’d be able to remove them with my lefthanded Crescent wrench, and I cannot.

Rusty Vandura - www.tinyurl.com/keepoppo > Phyrxes once again has a wagon!
02/09/2016 at 22:23

Thanks. I’ve seen that 5050 number come up elsewhere. I’ll check it out.