Comments on: Minimalist LED light detecting candle

By: Tony

Tony — Mon, 29 Dec 2008 22:33:11 +0000

Are there instructions on how to make? I am new to this and don’t know much about for example programming the ATtiny13.

By: MattieShoes

MattieShoes — Sat, 08 Nov 2008 04:04:43 +0000

If we’re going minimalist, we really only need one LED, right? It’d be easy enough during the flickering to test the ambient light, right?

I pronounce LED like “lead”, as in pencil lead…

Though I wouldn’t ever write out lead to refer to a LED… :-)

By: anon

anon — Thu, 06 Nov 2008 19:52:06 +0000

Made this exact same circuit for having blinking white LEDs all over my house for Christmas. During my tests the 2032 lasted about 6 mo with using the WDT in interrupt mode and having a 6s interval. So a year is pushing it but still pretty good. I don’t have to buy 2032s every year.

By: anon

anon — Thu, 06 Nov 2008 19:39:51 +0000

Just a quick note: High-Brightness LEDs typically show only a very small voltage as a light detector. Maybe not even enough to perform an A/D reliable on. I’m guessing that is why you see the older type LEDs in this demo. Test your LEDs before use. Of course a cheap old LED that is only used as a light detector is still much cheaper than a cDs cell, transistors, etc.

By: Eliot Phillips

Eliot Phillips — Thu, 06 Nov 2008 19:14:15 +0000

@Fool2cool Fixed. Thank you.

By: Sprite_tm

Sprite_tm — Thu, 06 Nov 2008 18:40:08 +0000

Fartface: I’m Dutch, and in Dutch, LED (or any pronounciation of it) doesn’t have a special meaning aside from the semiconductor photon emittor thingies. We all pronounce it as ‘led’ here (as one word) and I probably used it in my English explanation by habit.

By: gokul

gokul — Thu, 06 Nov 2008 18:39:45 +0000

Now _this_ is an LED hack.
Go go go!

(Why?:
1. Using the same LEDs as photosensitive devices (yes I know it’s a well known old idea (though many of us would be still be surprised such a thing could happen))
2. The minimalism of the circuit – the way it makes you smile when you look at the circuit diagram.
)

By: pokey

pokey — Thu, 06 Nov 2008 15:26:55 +0000

this is a good reference on both approaches: http://www.edn.com/article/CA6387024.html

By: pokey

pokey — Thu, 06 Nov 2008 15:23:42 +0000

@franklyn: LEDs are essentially photodiodes. They put out a small current when they’re exposed to light. Sprite is just using that fact in this project. The light-then-wait approach uses a different characteristic of the LED, something more akin to a CCD.

@fartface: It’s spelled “hobbyist”.

By: pb

pb — Thu, 06 Nov 2008 13:33:12 +0000

I think it’s because there are two batteries …

By: mikey

mikey — Thu, 06 Nov 2008 13:03:15 +0000

just two LEDs, a battery, an ATtiny13, and a battery.

did thy purposely put battery in twice?

By: fartface

fartface — Thu, 06 Nov 2008 12:48:11 +0000

what the heck are lead’s? Those look like L.E.D’s to me.

Why is it that most hobbiests cant pronounce the acronyms? It’s pronounced. Ellll EEEEE DeeEe
not lead.. See what happens when you guys dont go to college?

By: strider_mt2k

strider_mt2k — Thu, 06 Nov 2008 12:43:47 +0000

in jokes

super

By: maathieu

maathieu — Thu, 06 Nov 2008 11:12:12 +0000

Did you mention the battery?

By: Franklyn

Franklyn — Thu, 06 Nov 2008 05:13:25 +0000

How is the LED sensing performed here ? , all the material I’ve read on it requires that the LED is switched on , shutoff and then timed which doesn’t seem to be the case here.