Hi guys
I am building a dog treat feeder and need to build a circuit to drive a small motor for a specified time (variable).
The idea is when it is switched in, the motor will rotate a certain amount of revolutions and then stop.
Could some of you clever people please point me in the right direction.
Keep it as simple as possble, as I am fairly new- but willing to learn.
Thanks in advance
Regards
George

 

Your question is not clear. Are you expecting that you can control the number of revolutions by applying power to the motor for a fixed amount of time ? If so it is not likely to work reliably as the motor speed will vary with voltage and loading. Again if this is the case then you would be better off generating one or more pulses per revolution and counting the pulses. The difficulty in doing this will depend on the speed of the motor. For example if the motor is rotating at 10000 RPM then stopping it quickly enough will be almost impossible. If it only rotates at a few RPM then it will be easy. The more information you provide the quicker you will get a solution. For example motor type, power and voltage and speed rating and is it a geared motor ?

Les.

 

There have been previous threads about pet feeders. I suggest you search using the box at top right of the page.

 

Your question is not clear. Are you expecting that you can control the number of revolutions by applying power to the motor for a fixed amount of time ? If so it is not likely to work reliably as the motor speed will vary with voltage and loading. Again if this is the case then you would be better off generating one or more pulses per revolution and counting the pulses. The difficulty in doing this will depend on the speed of the motor. For example if the motor is rotating at 10000 RPM then stopping it quickly enough will be almost impossible. If it only rotates at a few RPM then it will be easy. The more information you provide the quicker you will get a solution. For example motor type, power and voltage and speed rating and is it a geared motor ?

Sorry for the lack of clarity.
It is a treat dispensor that needs to turn the motor “x” number of times then stop. The motor is geared and is connected to an augur. The system needs to run on 9 or12 volts.

 

There have been previous threads about pet feeders. I suggest you search using the box at top right of the page.

Checking those out at the moment.
Thanks

 

Might be better to use an Auger to dispense the food.

Otherwise use a gearbox motor drive with a opto pulse counter.

https://www.google.co.uk/amp/www.instructables.com/id/Automatic-Arduino-Powered-Pet-Feeder/?amp_page=true

 

A 555 timer circuit driving a Mosfet could be used.
Can you use just a time period or does it have to be a defined No. of turns?
Max.

 

A 555 timer circuit driving a Mosfet could be used.
Can you use just a time period or does it have to be a defined No. of turns?
Max.

Hi, thanks for your reply.
A time period would be great if it was adjustable.
Any ideas appreciated.
Regards
George

 

There are multitudes of 555 timer circuits out there.
http://www.learningaboutelectronics.com/Articles/555-timer-delay-before-turn-on-circuit.php
You just need a Mosfet device on the pin 3 output to drive a motor.
Max.

 

Thanks for the link, but having a look at the various circuits out there, most have to do with varying the speed of the DC motor. My problem is that I want to have to motor turn on for a duration and stop again. I really have no idea how to go about that.
I shouldn't said I'm fairly new to Electronics, and while I am enjoying it, I need a schematic or simple instructions. I would rather not simply buy a completed product - for the fun is making it.
Thanks

 

Thanks for the link, but having a look at the various circuits out there, most have to do with varying the speed of the DC motor.
My problem is that I want to have to motor turn on for a duration and stop again.

That what was the link showed, the 555 in a time delay?
Max.

 

That what was the link showed, the 555 in a time delay?
Max.

Thanks again. I found this schematic and tried it but it blew the 555 timer. Thankfully I bought a dozen of them. Can anyone on this forum tell me why it blew? My power source is a small 12 volt Lithium-ion battery. I checked and rechecked everything, but I am missing something.
The schematic I followed in here. http://www.learningaboutelectronics.com/Articles/555-timer-delay-before-turn-off-circuit.php
Thanks again for your help.

 

I take it you are not just driving an LED like in that circuit. Post your actual circuit, and picture, and that will help figure out what is going on.

 

What is the current/voltage of the motor?
You need a suitable Mosfet to drive it.
Max.

 

Thanks, the upload button wasn't working in Safari. But thankfully it works in Firefox.

 

What is the current/voltage of the motor?
You need a suitable Mosfet to drive it.
Max.

I don't have a motor yet, I was wondering if it was possible to do what I wanted to do. If I can get this to work, I will then work out the motor and gear ratio etc.
Thanks again for your help.

 

So motor runs for a few sec to deliver tid bit, but what is repeat rate. May need another 555 & counter ?

 

I don't have a motor yet, I was wondering if it was possible to do what I wanted to do. If I can get this to work, I will then work out the motor and gear ratio etc.
Thanks again for your help.

I seemed to have found "a" solution. It's a 555 timer with 3 Capacitors to turn on the relay for a specified amount of time. By adding or removing capacitors, I can get the motor to switch on and then turn off at a specified amount of time, eg. 3 seconds.
I'm sure there are easier ways to do it, but as I am relatively new to electronics, it's a solution
Thanks for all your help.
Great forum.
George

 

I figured this would work, but you have to have two separate power supplies.
If you just want to push a button when it is time to feed the dog you just use one 555 timer and calculate a pulse duration (1.1 * R1 * C1).
Use one 555 timer to provide a pulse that cycles between feed times. When one triggers, that pulse goes to a second 555 timer that operates an opto coupler (controls 2nd power supply) that powers the motor for your desired time.
There are seemingly endless examples of a 555 timers that have a pulse duration = (1.1* R1 * C1). I had to look at almost all of them to find what I needed. It turned out that it works as advertised and I needn't have spent all that time looking for something I could have calculated myself. Do the calculation for the 555 timer times and connect them, and use the output to the opto coupler to control the 12v to the battery. I'm not an engineer, and I don't have a schematic for this, but the one in the post #15 looks good, and you already have that.
I am currently dealing with OptoCoupler NTE3040.

 

I figured this would work, but you have to have two separate power supplies.
If you just want to push a button when it is time to feed the dog you just use one 555 timer and calculate a pulse duration (1.1 * R1 * C1).
Use one 555 timer to provide a pulse that cycles between feed times. When one triggers, that pulse goes to a second 555 timer that operates an opto coupler (controls 2nd power supply) that powers the motor for your desired time.
There are seemingly endless examples of a 555 timers that have a pulse duration = (1.1* R1 * C1). I had to look at almost all of them to find what I needed. It turned out that it works as advertised and I needn't have spent all that time looking for something I could have calculated myself. Do the calculation for the 555 timer times and connect them, and use the output to the opto coupler to control the 12v to the battery. I'm not an engineer, and I don't have a schematic for this, but the one in the post #15 looks good, and you already have that.
I am currently dealing with OptoCoupler NTE3040.

Thanks for that. I just connected the circuit to a 3d printed gearbox that I printed and it works beautifully. I connected the whole thing to a wireless trigger so that at the push of a button, a small treat is dispensed with a beep. I made this to distract the dog from barking and those passing by the fence, hopefully reinforcing good behaviour. I hope it works