Elliot you mentioned battery twice in the description :) Brilliant bit of work otherwise good job sprite you obviously know your stuff very well.

Posted at 6:58 pm on Nov 5th, 2008 by Fool2cool

Really slick! Nice work. Add a timer to the micro so that the LED’s turn off ~4 hours after dusk and it would make a great internal replacement for controlling solar garden lights. These things run all night and are usually dead the next morning. Your attiny 13 with a timer would leave energy in the battery for another night of accent lighting despite a cloudy day.

Posted at 7:28 pm on Nov 5th, 2008 by Tony K

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.

Posted at 9:13 pm on Nov 5th, 2008 by Franklyn

Did you mention the battery?

Posted at 3:12 am on Nov 6th, 2008 by maathieu

in jokes

super

Posted at 4:43 am on Nov 6th, 2008 by strider_mt2k

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?

Posted at 4:48 am on Nov 6th, 2008 by fartface

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

did thy purposely put battery in twice?

Posted at 5:03 am on Nov 6th, 2008 by mikey

I think it’s because there are two batteries …

Posted at 5:33 am on Nov 6th, 2008 by pb

@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”.

Posted at 7:23 am on Nov 6th, 2008 by pokey

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

Posted at 7:26 am on Nov 6th, 2008 by pokey

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.
)

Posted at 10:39 am on Nov 6th, 2008 by gokul

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.

Posted at 10:40 am on Nov 6th, 2008 by Sprite_tm

@Fool2cool Fixed. Thank you.

Posted at 11:14 am on Nov 6th, 2008 by Eliot Phillips

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.

Posted at 11:39 am on Nov 6th, 2008 by anon

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.

Posted at 11:52 am on Nov 6th, 2008 by anon

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… :-)

Posted at 8:04 pm on Nov 7th, 2008 by MattieShoes

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

Posted at 2:33 pm on Dec 29th, 2008 by Tony