Step 3: Schematic

The schematic is shown above, I've also attached a fritzing document for your reference.  This feeder is programmed to manually dispense food when the "set" and "volume" buttons are depressed at the same time.  By wiring light sensitive resistors across these buttons we can simulate the mechanical pushbutton action as follows:
When the photoresistors are not exposed to light their resistance will be very high and the processor in the feeder will think that the buttons aren't being pressed.  By telling the arduino to light up some LEDs near the photoresistors, the resistance will decrease low enough for the feeder's processor to think that the buttons are being depressed.
I've also attached two pushbuttons in the circuit so that I could manually turn the LEDs on for troubleshooting purposes.  These buttons are not essential to the project (but useful).
I also be diverted some power from the feeder's four D batteries to power the arduino.
not trying to be rude but can't you just set the automatic feeder to idk automatically feed your dogs... but fun looking project
<p>Hi Amanda,</p><p>Could I ask you some questions in private?</p>
Hi Amanda, great project! I thought I would do this for my senior project at school. Instead of using photoresistors and leds, using a simple transistor with a 2.2K resistor on the base, connecting the emitter to the ground side of the button pad and the collector to the positive side of the button pad would be a more cost-effective and time sparing solution. Also, I would put in piece of code that would post a tweet after the feeding procedure was completed to prevent overfeeding. But thank you, great idea, and this instructable will certainly come in handy.
That's what I was thinking, why not some transistor, maybe because of the power flowing through it to control the pet feeder.
I have gotten to the step where you attached the Ground from the D Battery on the feeder to the PCB board. I must have put it on the wrong area as one of the LEDs is constantly lit. Do you have an exact spot to put it? <br> <br>Also, do you have a part number for the Test Buttons? I can't find them. Great project though!!! I am almost done with mine.
Is the USB cable just for the initial program load? You can disconnect it after that, right? <br>
Definitely a cool project, but 1 question, why use photo resistors and LEDs in stead of just straight transistors or some form of switching circuit? Seems like a bit of a roundabout solution
I would love to see more of an explanation of how the arduino code works. Great project!
This is a nifty bit of work......however......I would NEVER be too busy to get home to your dog! I love English Bull Terrriers. Sadly ours died last year but we are now ready to invite another Bully into our home. <br> <br>If it isn't an English Bull Terrier......it's just a dog! <br> <br>Apologies to owners of other breeds, I'm sure you feel just as passionate about yours.
Great project! But what prevents the dog from shredding it into pieces? :P
just dont loose your phone or your dog might famish:-)
This is too cool! I am really bad with electronics but I will have to learn the basics so I will be able to make this soon.
that is one awesome project! My dog Buckley would love this.
i have been wanting to do something like this

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Bio: I'm a grad student at the Center for Bits and Atoms at MIT Media Lab. Before that I worked at Instructables, writing code for ... More »
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