Dangerous Prototypes

In development => Project logs => Topic started by: voidptr on February 17, 2012, 06:37:27 am

Title: Re: Vetinari's Clock
Post by: voidptr on February 17, 2012, 06:37:27 am
i'm also playing with this :o)
i got a cheapo clock last weekend and i hacked its "core" :-)
right now  it's clocking on a breadboard, 
i'm testing few weird ways it can clock the time  :oP

interesting one is going faster when the hand go down and slower when go up :o)

i'm also looking for a way to update the timing table, without having to recompile, maybe  a kind of rs232 interface to my computer ...

:o)
Title: Re: Vetinari's Clock
Post by: voidptr on February 17, 2012, 07:23:09 pm
lol

small parts flying around 8o/  this is why i choose a $4 clock for the first try :o) 
i can torture it like this !  :oP
http://http://www.youtube.com/watch?v=jCNBab4LeXc
Title: Re: Vetinari's Clock
Post by: BrentBXR on February 18, 2012, 02:31:12 am
So its just a clock that ticks randomly? Where did you get the little module that is the actual stepper/hands?
Title: Re: Vetinari's Clock
Post by: jbeale on February 20, 2012, 07:41:32 pm
LiFePO4 charging is cc-cv. Constant current, then constant voltage. A standard adjustable current bench supply will work.  Adjust voltage to 3.65 V and current to C/2.  (C=capacity in ma-hours).  If your cell is 1000 mAh, limit charging to 500 mA.  Don't leave it at 3.65 V forever after it's done; if you want to "float charge" you should drop back to 3.5 V.

Edit- I looked at your photo and see your 18500 size cell capacity is 600 mAh. So, limit your charge current to 300 mA. It will take a little bit over 2 hours to charge if it is empty. Note, it is empty you should charge it if the cell drops below 3.1 V when resting (usually the "damage threshold" is 2.0 V). The discharge curve of LiFePO4 is amazingly flat, it's between 3.3 and 3.2 V almost all the way down (assuming you aren't drawing too much current).
Title: Re: Vetinari's Clock
Post by: charliex on February 26, 2012, 07:53:38 pm
our blinky ball has a LiFePO4 charger in it with a really nice chip
http://www.032.la/svn/listing.php?repname=032&path=%2FNSL_LED_Ball_1S%2F&rev=1051&peg=1051#ada847e1cd2f01bdf1681e67a5ce64f18

eagle brd/sch files for the slick have it.
Title: Re: Vetinari's Clock
Post by: voidptr on March 02, 2012, 09:25:44 am
@MickM

Aaarrrrgghhh! im not lucky  :( 
i just removed my steady 5 volts from my proto on breadboard and replaced it with 2 NiMH giving my around 2.5V
and now it is not enough to move the gear for a tic, is just wiggle :o(
did you try how long you can go before your motor stop ?
i will need play with those resistors to pumpup current and have my cheap motor tic again !
:o)
Title: Re: Vetinari's Clock
Post by: voidptr on March 02, 2012, 06:41:24 pm
lol
i guest i was to asleep :OP
i wanted to say :  "did you try how LOW (voltage current) you can go before your motor stop ? "
my junk motor seems to need at least 10mA... going on 2AA it fall below that and stop ...

btw my clock made it first victim, one of my friend find it "distracting", earring irregular "tic" seem to works ! :o)

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