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I purchased a Christmas village from Walmart on sale after the holiday season (Holiday time 30 piece Mini House Set). The 5 houses take 2x AAA batteries each, but I converted them to DC plugins already. While I was doing that I noticed the streetlights in the set had hollow tubes and the globes were removable, so obvious we need to install LED lights in there. Here's where it gets tricky because the area is so small I need to figure out how to deliver power.

I've using 0603 SMD LEDs with leads on it that I'm piping down the light pole to the base. I have room for a small PCB at the base but not much.

I'm thinking for power delivery I'd like to do some pogo pins to a pad. I have some very tiny rare earth magnets I can put on both sides to ensure they attract and "stay put."

Ideally if space allows I would like the lamps to be polarity agnostic (my wife will setup the village and tear it down and I don't want her to have to worry about which way to orient the lamps), so I'm thinking a bridge rectifier with schottkey diodes (if I can find smd ones small enough to fit in the base with the pogo pings and magnet)

There will be 5 "power delivery" pads connected in parallel back to a DC power supply. I'm thinking about tying to use the same power supply that the village houses use at 3vdc, but the bridge rectifier is looking at about .6V drop and forward voltage for the 0603 is 2.7 - 3.0v on data sheet for the LED. So I'm concerned that I won't have sufficient supply to illuminate the streetlamps. I could install something upstream near the DC power supply that would bump the voltage up for all 5 parallel paths but before I go looking into that, are there other compact ways I could achieve polarity agnosticism without the voltage drop?

Thanks!

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  • \$\begingroup\$ As long as the LEDs can withstand reverse voltage of 3v, you could make your town’s power supply AC. Realism! \$\endgroup\$ Mar 12, 2023 at 19:08
  • \$\begingroup\$ For wiring I would use wire wrap wire soldered to the LEDs. If you have enough room you might be able to put a piece of 1000m plastic fiber optic into the light pole and keep the LED at the bottom. \$\endgroup\$
    – Gil
    Mar 12, 2023 at 19:36
  • \$\begingroup\$ I've got leads on the LEDs already, most of the fiberoptic lighting I've seen is very directional, although this would allow me to just use one LED and light all the lamps with it if I could figure out a good 1/2 sphere coverage. \$\endgroup\$
    – Sloanstarr
    Mar 12, 2023 at 20:42
  • \$\begingroup\$ An essential difference between incandescent and LED is that incandescents are self-current-limiting; they become reasonably ohmic once they start glowing white. LEDs have no such ability and are prone to thermal runaway (overheating causes increased current causes more overheating). \$\endgroup\$ Mar 12, 2023 at 23:01

2 Answers 2

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If you could find bipolar white LEDs you could use those.

Alternatively, put two LEDs inverse back-to-back. Only one will light on DC.

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  • \$\begingroup\$ I had the 0603s leftover from a different project, I was going to try and use those, I'm not sure if I can fit 2 LEDs in the globe, maybe I'll look for bipolar LEDs. \$\endgroup\$
    – Sloanstarr
    Mar 12, 2023 at 20:37
  • \$\begingroup\$ What if you put them literally back to back? (bottom to bottom?) \$\endgroup\$ Mar 12, 2023 at 22:19
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I have some very tiny rare earth magnets I can put on both sides to ensure they attract and "stay put."

Super simple: Magnets have polarity too.

Use magnets in both lamp and base, and orient them so they reject (push apart; refuse to seat) in the wrong orientation.

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