LED traffic-light teardown

Pretty kewl.

From Technology Connextras on the yootoob, he makes like The Big Clive in tearing down a surplus LED traffic-light to show its innards.

I gotta admit, it’s not at all what I was expecting. :))



Very cool. I have seen his videos before.

The source video is a hoot, too. :laughing:

Also excellent video.

pretty much every light in nyc has green led clusters fail, some have few clusters out, some have so many that half the light is out. reds otoh, i almost never seen even few leds fail.

our lights are not made the way it is in the video.

Yeah, most of ours use the clusters also. I’ll have to start paying attention.
All the Best,

Most traffic lights here in the US use the led matrix and yes, they do fail. I think the ones in the UK are made differently. There are stull incandescent ones where i live, but LED has pretty much taken over (even streetlights).

A loooooong time ago, I made my own LED dome lights as a matrix of 5mm LEDs on perfboard, as 3S strings in parallel (no idea how many). Beautiful!

But after a while, a few strings started flickering, just like you see on those notorious walk/don’t-walk signs. Wtf?

Was only pushing 25mA or so per LED, when 20mA could easily be handled. And I don’t keep the doors open for too long.

All it takes is 1 LED to start flickering, and it takes the rest of the string with it.

Don’t recall if any strings fully went out, but it was rather annoying.

Good videos, thanks for sharing.

Not what I expected either….

Interesting video.
Seems solid, and simple.
Grabbed this screenshot (rotated)

Very interesting — thanks for sharing it, Lightbringer.

What’s very curious is how there’s no thermal compound between the MCPCB and the heat sink. I guess it’s machined to be very flush by the tightened screws? And perhaps also since there are 8 separate LED’s, it means they’re not driven very hard. The power supply module looks overbuilt… meant to last a very long time. I’m guessing that the switch controller is in the traffic light pole somewhere near the bottom for servicing.

If the rating was… 18W?, then that’s a little over 2W per LED, so there’s a good chance those are 3W “bead” type LEDs. Lots of surface area to spread the heat around, and with a 50% duty cycle on average (way less for arrows and yellow), it seems pretty conservative. And 12” across is pretty much a pie-plate, so ain’t too bad.

The PS is just on/off, 120V to whatever. Just like a dumb bulb, it gets wired in and that’s it, so yeah, the “smarts” are down in the box somewhere. Used to be the old mechanical “music box” spinners, later all electronical.

When Portland Oregon switched over they had a display. The new lights used 10mm emitters covering the entire size. LED’s do not produce enough heat to keep the lens from freezing up. This was a better design is since the heat was next to the lens. I went and got the old bulbs which were rated for 8000 hours.n

He’s a funny guy, in his particular nerdy way.

Good to see you still around here, btw.

Yeh, he had that Eddie Muenster thing going on before the ponytail. :laughing:

Hmm, you’re the second one today saying that.

I’m starting to feel like Snake Plissken. :stuck_out_tongue:

Weel, i’ve been absent from BLF for over 2 years, so it’s nice to see familiar posters still posting.
Many seem to have left though, many new members too.