Simplest possible LED circuit?
August 7, 2014 9:42 AM   Subscribe

I want to place small red LEDs into the eye sockets of local statuary. What do I need to buy?

A man needs a hobby. My thought is buy a bag of cheap red LEDs, a bag of coin-sized batteries, and some poster putty. Hook the LEDs to the batteries, slap on a dab of poster putty, and voila!--That statue that folks walk by without noticing will now stare down at passersby like a Cylon, at least at dusk and until the batteries run down.

Ignoring for a moment any legal and ethical complications to this plan, what are the technical aspects? I know nothing--nothing--about electronics. What do I buy and how do I put it together? How long will the lights last? Ideas for additional options are also welcome.
posted by LarryC to Technology (11 answers total) 16 users marked this as a favorite
LED Throwies
LED Stickies
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posted by phunniemee at 9:44 AM on August 7, 2014 [8 favorites]

Yep, you can hook LEDs up directly to 3V lithium coin cells, but you can also use a resistor to increase the battery life. This is especially true with red LEDs. In depth info here.
posted by zsazsa at 9:53 AM on August 7, 2014 [3 favorites]

Thanks, friends, those links are just what I need. Any idea on how long these will last before the batteries run down?
posted by LarryC at 10:07 AM on August 7, 2014

A little analysis on battery life for throwies if that helps. (Sorry, double posted this. EMS didn't design the throwie)
posted by JoeZydeco at 10:25 AM on August 7, 2014

Behold the Master.

okay, it's been enhanced slightly with PS but the light really did beam like this, just couldn't get a good angle because it was in the middle of some crazy traffic. For an idea of how tall the statue is, these google images are similar.

Sadly, a year later the lights weren't working anymore.

posted by TWinbrook8 at 10:58 AM on August 7, 2014 [3 favorites]

Add resistors to the big bag of led's and coin battery and you are good to go.
To add complexity ( More power as you add more things. 9V Battery holder + 9V battery will be a good starting point)
- Arduino to program how often the led blinks.
-Internet shield addon to control the blinking by wifi.
- IR sensor to detect people and then blink
- Small speaker to trigger Cylon MIDI /BSG Sounds
- Small DC Motor for movable hands.
- Bonus add on Add Lasers to blind people( Warning: do not blind people)
posted by radsqd at 1:37 PM on August 7, 2014 [1 favorite]

Use a tiny solar panel out of sight on the top-rear of the head, instead of a coin cell. The lights will operate for years (ie until someone takes it down), daytime only.

Go to a thrift store, get old solar garden lamps, then you have LEDs that charge during the day and switch on at night.

But I think it might be more effective to use just the solar panel directly, and white LEDs, so because it's daytime, the eyes seem to glow, but you're not really sure if it's real or just some trick of the light...

Be considerate of wastefulness and environmental impact. Using up resources as a joke is the epitome of disposable culture. Minimize that squandering aspect where you can. The joke is funnier if it doesn't come at cost.
posted by anonymisc at 2:51 PM on August 7, 2014

I found a really tiny circuit once that just had an LED, a coin cell, and a photoresistor. I can't find it now, but this one,this one looks good too: (with phototransistor and normal transistor) . It was like a throwie, but the circuit only connected when the photodiode didn't have light on it, so the LED only came on after dark. It meant you could make a throwie that woud last twice as long. Mine only lasted for a month or six weeks, though, so either I built it wrong, or throwies really don't last very long.

Still, it's a cool idea.
posted by lollusc at 5:56 PM on August 7, 2014 [2 favorites]

Actually, reading the details on that page, a month for the dark-detecting one seems about right. Probably only a few weeks for the normal throwie.
posted by lollusc at 5:57 PM on August 7, 2014

You might want to check into LED's with built-in resistors, which could simplify things somewhat.
posted by jgreco at 5:19 AM on August 8, 2014 [1 favorite]

Don't know that anyone will see this followup questions--but which resistors should I buy? Anyone have a link to a specific type?
posted by LarryC at 2:19 PM on August 17, 2014

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