Wrist Watch and Servo motor

[badgers]

I am sorry if this is off topic but my google searches have not resulted in anything usefull.
I want to make an automatic dog feeder.
I want to use a cheap digital wrist watch as a timmer so that I can set it to go off every day at noon. Actually the watch can be set to go off M-F at noon and not go off at all on the weekend, since I am home.

Does anyone have an idea on how to take the alarm signal and get it to drive a high torque servo?

any help is apprecated, this will be powered off of a wall wart transformer and I will use an LM317 to get a low voltage for the watch, and to power the servo. I think 1.5 amps should be enough.
I can even add a big cap on the circuit since the current will be low for 23hrs and 59 min of the day.

thank you for your time and have a good day.

[Pete P]

Connect the output of the small peizo to a trans. to short a servo tester's control knob. I dont know exactly how to do it, but I put this idea on the table.

[Dan Baldwin]

If I were doing this (I just feed my dog in the morning) I wouldn't open the watch, I would use a small microphone with a transistor amp to signal a PIC to move the servo. Actually, if I were using a PIC, I guess I could build the clock into it, and eliminate the watch completely.

Dan

[Zeta Phoenix]

if you want to go the moded watch way, my watch, a Timex expedition has alarms that will only go off on weekdays, but would recemond going the PIC route.

-Jon

[Pete P]

I completely missed the 'not on weekends' clause :-)

[MAVA]

I would use a heating (electronic type)and A/c controller.

Many are under 20 to 25 bucks, some operate off two AA cells, relay output.

Would work well for battery charging as well.

Check it out..

Martin

[pic man]

id use a pic,, rather then a watch, program in a timer, conect it to a serve atached to a trap door, with some fiddleing aorund , with times , timers , and how long to open the trap door, jualla a dog feeder WITH OUT A TACKY watch, which functions perfectly

one thing to think about when opening a watch is its electronicly prouduced to specs which are hard to recreate by hand, ie it solders much smaller contacts then humanly posible,

pic hooked up to a 555 timer ic, set to oscilate 1 time per seocnd, pic counts these pulses to justify time pasage
x pulses = 1 min
60 mins = 1 hr
24 hrs = 1 day
threw this,, u get a timer, one you would have to start when u want the dog fed, then you can forget about it. you will work harder to use a watch then not to


fyi a bs2 chip cost 50 $ , will teach you to program it, and controll a srvo, i believe its capable of a 24 hour timer, if you workvaribles right and since you prolly never plan to make another fo these, spending the 50 $ to do exactly what u want might niot be a bad path, and will open your eyes to pic incase you decide to make 2. power suply for this method will be a bit more dificult as the bs2 needs 9 volt dc suply to run a servo, but i bet with proper motivation a power suply could be devised, fyi i sugest a homework board for ya,, radioshack for 80 $ comes with the book to teach you to program it,
NOT the way to go for prouduction,
prolly the way to go for you

[Peteohms]

Whats wrong with a plane electric timer?

[pic man]

ii just think it would be all around easier to runa timer on a pic, and keep all of it within the pic,,, then trying to integrate watches n such

[vintage1]

I'm with MAVA. Cnteral heating contrlloers have everythiung you want and indeed if you buy the guts ftom a motorised valve, you have a highish torque 'servo' as well.

(A motorised valve is a motor and limit switch that is designed to turn a water valve abou 1/4 turn, and open up a pipe: they are not hugely efficient or powerful, but come with enormous reduction ratio gearboxes and generate decent torque, albeit slowly).

[flieslikeabeagle]

How about a lawn sprinkler timer? I see these in the $20 range often, they are usually programmable for times and days of the week, and their output normally drives a solenoid valve. Many are multi-zone, i.e. they can drive several solenoids independently on different schedules.

My thought is to put the dog food in a container with a hinged bottom, The hinged bottom would have a small permanent magnet glued to it, which would hold it shut by being attracted to the head of a suitable electromagnet attached to the container. When the timer goes off, it will energise the electromagnet, and if the polarity is correct, it will repel the permanent magnet, popping the box bottom open and dropping the food. The solenoid would be turned off the rest of the time, so quiescent power consumption would be low.

Not quite sure how to do this five days in succession, unless you build five identical boxes and mount them one above the other. The solenoids should be energized in sequence from bottom to top, so on Monday the bottom container empties into the dog's dish, on Tuesday the one above it empties through the already open box below it, and so on. You'd need a sprinkler timer capable of controlling five solenoids on independent schedules, though. I frequently see four-zone sprinkler controllers, but I don't think I've seen a five-zone one, though they're probably available.

I hope you don't encounter power failures in your area, or you will have one hungry, thin dog when you next see him/her. :eek: Maybe you also need a webcam hooked to a Linux PC running Apache, so you can ocassionally check on the status of the dog feeder by looking up the relevant web page. :)

-Flieslikeabeagle

[thanhTran]

badgers, there are hundred of ways to do what you want :)
if your wrist watch has the alarm function you can use the speaker signal to signal a PIC to drive the servo. Need to limit the voltage from the watch's speaker though.


You can also use PIC to work as a timer like some people suggested above

You can also buy a electronic timer from Target (the kind to turn on/off lights when you're not home) for $15 and you can program it to turn on on the time you want, then on the output, use a transformer with a solenoid to open the food door ;)


flieslikeabeagl
How do you configure Apache & a webcam to ve a webcam server? Thanks

Thanh

[flieslikeabeagle]

Thanh, I've run Apache (on an intranet in my classroom), and I've used a webcam on Linux, but I've never combined the two myself. However, off the top of my head, I think all that's needed is a frame-grabber for the webcam, and a CGI script on the server that writes a dynamic HTML page with the freshly grabbed frame inserted as an image. Every time you reload the page, you'd get a new snapshot.

There are probably more sophisticated ways. Here's something Google turned up: http://www.aboutdebian.com/webcam.htm

-Flieslikeabeagle

[badgers]

thank you all for your replies. I have taken apart a give away digital alarm clock and I am working with it.
I am not going to use a servo. I will use a DC motor and an end limit switch.
The feed bucket will just make one revolution per feeding. This allows for a larger “hopper” to fill the serving cup. (start/stop point fills the cup) 180 degrees away drops the food.
The alarm clock has two catches.
1) it runs at 3.3V and the alarm does not stop until a button is "pressed"
I will be running 12VDC motor thru a relay.
a LM 317 will give me the 3.3V to run the clock.
I will use an NPN bjt to shunt to ground the trigger on a 555 timer.
This will be set up as a one shot. the 555 output will go through an NPN emitter follower to drive the relay coil with a catch diode.
The end switch will be OPEN at the end point not closed (SPDT)
The end switch will be in parallel with the emitter follower so that once the motor turns past the “end point” the switch will hold the relay closed. The one shot will be timed out to be about half of the revolution. The end switch will give consistent turn off of the motor through one revolution.

There is a third NPN bjt to tell the alarm clock to turn off. This is fed off of the output of the 555 timer as well and just “shorts” the button contacts together. I am using a capacitor from the base to ground with a 1K resistor. The time constant for this RC network is just to make sure the motor has gotten off of the end switch before shutting down the alarm. There is always a little slop in the switch.

Thank you for your time and have a good day
Mike