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lancelot
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Posts posted by lancelot
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Sorry, was thinking of track lighting
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Guess someone is gonna have to buy one and reverse engineer it...
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The Blinky Lights Company's ad doesn't say how big is its battery nor does it say how long the battery lasts
It says they use a CR927 which if you reference Wikipedia's handy dandy battery guide (http://en.wikipedia.org/wiki/List_of_battery_sizes) says that it's a 3V 30mAh cell (the blinky lights company says they use 2 in each brooch).The LEDs blink! Therefore they are turned off for 98% of the time, so the average battery current is low.
My bad, I made the assumption that you knew we were talking about blinking brooches. But in reading back, I guess there wasn't a reference of that until now :-[
So, what is the calculation used in determining how long your 2 CR927's (or other lithium type cell) will last? (based on 4 or 5 bright leds flashing 2% of the time each? so say in total it would be like 1 led on for 10% of the time). -
So, based on our conversation, I understand that you're saying it's impossible to have a nice bright christmas tree brooch that lasts more than a few hours without replacing the batteries? come on man...if you're not saying it's impossible...then how is it done? with 2V @20mA bright leds? a 12V car battery? :P
here's a little something that will bake ur noodle :P
http://www.flashingblinkylights.com/ -
Aren't halogen lamps powered up by a cap. or ballast of some sort? (i.e transformer)
that would mean there's charge and discharge time...would make it really hard on the hardware to be "flashing it" no? -
I'd imagine that there's software that can draw the PCB...hours and hours in front of the PC I guess...but you would have gotten it done over a year ago!? :P
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okay, found some specs that you two might find interesting...
http://www.vishay.com/leds/miniled/
if you look at the "low profile" Red, Yellow, and orange they are all 1.8V @ 2mA
Now a CR2016 Lithium Ion coin style watch battery is 3V...and delivers approx. 90mAh (according to http://www.gregsearle.com/rex_batteries.html)
Or you could use 2 - AG3 (Silver Oxide) coin batteries (1.55V @ 45mAh each) which would bring you to 3.1V @ 90mAh
So, IF I'm using one L.E.D. (scale appropriately for more L.E.D.'s) at 1.8V @ 2mA, how long would the 2 - AG3 3.1V @ 90mAh cells last?
Would this be the correct calculation?:
L.E.D.: 1.8V * 2mA = 3.6mW
2 - AG3 cells: 3.1V * 90mAh = 279mWh
so take one divide the other and get 77.5 hours? and that would be on continuously?
So, there's the numbers you do the math...maybe those custom christmas pin flashers have some caps or ic's in them to increase the battery life, I don't know for sure. -
I know it's a bit late, but better late then never :P
use 3mm leds, and no, they do not take very much power...using a 9V is a bit overkill, but you won't notice it on the leds as they draw a very low amount of current...using a 9V battery would mean that your circuit would last a very very very long time. a small watch battery is enough to power many small 3mm leds...look for the specs on the current draw on the leds and check out the amount of mAh that a small watch battery will provide...with these two numbers, you can calculate how long they will last. -
This is somewhat what I'm trying to accomplish...can you add any comments? assistance?
http://www.electronics-lab.com/forum/index.php?topic=9409.0
BIG LED Clock project
in Electronic Projects Design/Ideas
Posted
Dunno, but if you follow the link, the schematic is laid out to the public, no need for a password or payment or anything. If you buy anything from that link it's the finished project.