my first project - Page 1
Forum section: electronics / projects

author: kenichi
author_rank: Newbie
timestamp: November 03, 2013, 07:23:36 am
content: i wanna build a pet feeder but i need advice..i am uncertain to what kinda transformer to use as i havent know what type of motor have a strong turning power. any fan will do .where can i learn how to select the right component for my project?please direct/advice me on what to learn..i am on my final year diploma in E&E engineering i seem to be able to use some theory to make a circuit for this project but if there's any other way besides using experience to select type of component please advice me ..i tried surfing circuit design.. but most lecture videos on circuit design are about microprocessor which is unrelated to this practical project.if there is a course /book/ video that i need to know to design this circuit please let me know..this project also need to use an ic ...perhaps i can use 555 +capacitor+variable resistor to make delay but ... if you have any other ideas please share with me..the condition that my lecturer gave me is that no programming is allowed..and there will be a question session later on about "the reason why i choose this particular component why not something else?" what should i do so that i can design a practical circuit and answer all their question confidently.. if u guys have any suggestion on what i should learn please tell me and i will look it up...

author: Gatos De La Muerte
author_rank: Contributor
timestamp: November 03, 2013, 05:53:13 pm
content: HeyI like the idea "no programing is allowed", I can't really help you with choosing the specific components, but one thing I would consider is instead of using a powerful motor that would just crush any kind of pet food that blocks the motor,why not try making a small circuit that would drive the motor back and forth to shake it off, if no food is detected after a certain amount of time.It might add some complexity to the circuit, but in my opinion it would work better in the end.

author: yogece
author_rank: Contributor
timestamp: November 03, 2013, 06:30:20 pm
content: hi,i could help you to design the circuit without programmable thing,but what about the mechanical setup motor power rating

author: Unknown
author_rank: Unknown
timestamp: November 04, 2013, 12:55:16 am
content: A screw arrangement for the dispenser might be less prone to jamming?You'll have to think about your IR setup too - either heavily shroud the detector, or modulate the IR transmitter & detect that modulation in the receiver - to prevent interference from ambient light.

author: minime72706
author_rank: Frequent Contributor
timestamp: November 04, 2013, 01:08:27 am
content: I tend to avoid mechanical stuff (motors) myself for no real good reason, but I can maybe offer some advice anyway. Bipolar stepper motors have good torque and you can measure the back-emf of the motor to determine if it is stuck or not.

author: kxenos
author_rank: Frequent Contributor
timestamp: November 04, 2013, 01:20:24 am
content: I would start by calculating how much torque is required to turn the flap. That would had to do with the weight of the stored food, it's granularity and the friction. It would also depend on the mechanical design and the gear ratio used. Then, if I knew the required torque, depending on whether the motor has to rotate in both directions or not, I would choose a motor type. Stepper motors can be preciselly controlled but they are expensive and require complicated logic so they're probably out of the question. Simple brushless motors could be fine for this application. Then I would find a motor with double the calculated torque just for margin. Then I would check the datasheet of the motor and design the driving circuit with double the required power. Then I would determine the transformer to match the power requirements of the driving circuit.Just my 0.02$.

author: deth502
author_rank: Frequent Contributor
timestamp: November 04, 2013, 04:20:27 am
content: i think the ir setup is needlessly complicating things. i like the screw feed idea. positive displacement. the screw turns for x number of times and you kno how much food has been distributed.is the ir setup designed to detect the food coming out to determine how much was dispensed? or to determine the presence of said pet to start distributing the food?? if the former, again, positive displacement screw. if the latter, simple switch.

author: kenichi
author_rank: Newbie
timestamp: November 04, 2013, 07:20:34 am
content: Quote from: kxenos on November 04, 2013, 01:20:24 amthank you soo much , i really appreciate your suggestion.. the approach is just wonderfully superb.. thank you sir...

author: kenichi
author_rank: Newbie
timestamp: November 04, 2013, 07:25:30 am
content: Quote from: deth502 on November 04, 2013, 04:20:27 amthe ir setup is to detect the presence of the pet.. functioning like a switch ...yep i like the screw feed idea better but what about the availability of the screw like where to find ? and what about the cost.. i personally dont know how to make or find the screw needed..thats why i wanna use a rubber edge / silicon propeller..

author: hedgewallace
author_rank: Contributor
timestamp: November 04, 2013, 08:08:29 am
content: I saw that the Ben Heck show recently did a project for a Doggie Treat Dispenser. It seems pretty cool.Part 1:Part 2:Part 3:

author: deth502
author_rank: Frequent Contributor
timestamp: November 04, 2013, 09:09:47 pm
content: Quote from: kenichi on November 04, 2013, 07:25:30 amhttp://www.ebay.com/itm/Bosch-ASPMT24-1-1-2-Inch-by-13-Inch-Spur-Auger-Bit-/330423579934?pt=LH_DefaultDomain_0&hash=item4ceec7b51ein a small length of 1 1/2" pvc pipe.of course, there are many sizes larger and smaller as well, whatever fits your needs.and the activation switch can be as simple as a micro switch under a hinged plate in front of the unit.the switch activates the motor and runs if for x turns, then starts a timing sequence limiting how frequeltly the switch can be activated.

author: hammy
author_rank: Unknown
timestamp: November 04, 2013, 10:56:42 pm
content: Quote from: deth502 on November 04, 2013, 09:09:47 pmRight. If the dog-brain can do some of the work you can "offload" your circuit.