thats what i did... i just picked up 2 x 3-cell AAA holders.
im going to change stuff around a bit, and add the switch and Vreg to the board with the battery holders..
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thats what i did... i just picked up 2 x 3-cell AAA holders.
im going to change stuff around a bit, and add the switch and Vreg to the board with the battery holders..
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And then...and then...and then...you could...ummm...ummm...put another PCB on top of that one...and then...and then...and then...put 9v worth of small solar cells on that...to..umm...ummm...umm...trickle charge the AAA's...Originally Posted by dragons_fire
Are you planning on using a linear reg or switch mode?
Check out the LM2825-xx types. Self contained, DIP28/.6", a bit thicker than normal DIP28 types, but have the coil and everything inside the package. And it'll save you some power.
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to be honest, i dont really know much about voltage regulators (or anything). im using this reg: http://www.st.com/stonline/products/...035/LD1084.pdf
it may not be the best, but ive used them before, and i have some laying around...
and... and... thats why there is so many headers with pins going nowhere right now.. just so i can add more boards on top...
should mention i did look at solar panels.. one the size of this robot, would output around 20mA at 6v. just not worth it.. it would take forever for that to charge enough...
Last edited by dragons_fire; - 19th April 2007 at 06:20.
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That's a linear regulator, but it is a low-drop-out type. Don't know how much you know about regulators, quick explanation:
Linear - takes voltage in, say 10v @ 1amp, you want 5v @ 1amp, it dumps off 5v @ 1amp as heat, 5watt wasted...in this case, 50% efficient.
Low Drop Out - All regulators need some overhead to work right. A 5v regulator might need 7v at full load to work, below that, things go haywire. A Low drop out type might only need 5.5v input under the same conditions
Switch mode - takes that same voltage in, turns a mosfet on/off really fast and uses an inductor to help keep an output cap charged up to the regulated voltage, but there's just a tad bit of ripple on the output (which can be smoothed out). It's not 100% efficient, but depending, they can approach 98% under the right conditions.
Well, I was just thinking that there will be days when it's sitting not doing anything...and if you had any laying around, they'd help...should mention i did look at solar panels.. one the size of this robot, would output around 20mA at 6v. just not worth it.. it would take forever for that to charge enough...
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to be honest, i really dont know that much about electronics in general.. i learn by seeing what other people have done, and putting stuff together and trying it till it works..
that switch mode regulator, cost almost 20 times as much, and i dont really have much room on my board for it, (it looks like its about 5 times the size).
we have lots of floor area that gets sun most of the day, so its not entirely out of the question for solar panels.
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Guess I should've checked the price before I mentioned it. Digikey is getting $30USD for them nowadays. Back when I bought them, they were only about $8USD. There's got to be a better option out there.
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so here it is... power board is done, and works great... the main board underneath, is the old one thats not working.. i havent made a new one yet..
batteries are duracell AAA 1.2V 1000mAh. i havent measured current draw on the motors, but the datasheet says 50mA no load...
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