Motor won't spin! Help!
Chip_McCallahan
Posts: 10
in Robotics
Hey, everyone!
I have a question. I can't make a regular motor run in the Propeller chip (I have the Activitybot). What I want the robot to do, after detecting heat, is make him blow out a candle with some fan blades that I will put on the motor. I can't make it spin without connecting it to a direct output which pulls power away from the other devices even when I connect it to a 3.5 volt output. I figured out how to make the IR sensor detect heat, so I'm using the IR sensor for heat detection.
P.S. I am new to the forums.
I have a question. I can't make a regular motor run in the Propeller chip (I have the Activitybot). What I want the robot to do, after detecting heat, is make him blow out a candle with some fan blades that I will put on the motor. I can't make it spin without connecting it to a direct output which pulls power away from the other devices even when I connect it to a 3.5 volt output. I figured out how to make the IR sensor detect heat, so I'm using the IR sensor for heat detection.
P.S. I am new to the forums.
Comments
Tell us more about your fan motor, i.e. what voltage is it designed to run on; how much current does it draw?
-Phil
If you're looking for something quicker, the single-relay module will about do the trick:
https://www.parallax.com/product/27115
You can probably use one of the unused servo header pins on the Activity Board. Set the power jumper to 5V.
Well, I don't know about the idea for the I/O pins because it is a two-pin motor which is why I hooked it up to a 3.5V output. Should I post a pic of the motor?
I don't exactly know how much voltage it draws. I guess it varies with however much voltage you put to it. Would a picture of it help?
And, thanks for the welcome!
In any event, you will not be able to drive it directly from a Propeller pin. As Gordon suggests, you will need a transistor driver.
-Phil
Here's a photo. Please note: I put the solid core wires on myself.
2. Does it run fast enough when you connect it directly to the 3.3V power supply?
3. If not, how about 5V? (It may actually be a 1.5V motor.)
4. Is there anything printed on the motor to give you a clue as to its ratings?
-Phil
I just checked the motor. I can't find any mark on it that will give me any idea. I think I said that I hooked it up to a 3.3 volt output (I may have said 3.5, but I meant 3.3) and it drained power away from the other devices.
Yes, I would say it runs fast enough when connected to a 3.3 volt output, but, like I said, it drains the power from other things, so I don't know what to do.
The resistance is about 2.6 ohms.
Thanks, but how do I control the on/off and where do I wire the transistor switch?
If you really, really want to use the transistor, know that Google is your friend. Type in a search like 'turn motor on with a transistor' and read the pages and look at the images.
There might be some diagrams here but not all of the images are working right in the forum. Lots of stuff missing. No matter; this is a small piece of the Internet.
On the voltage to use: you probably know you want a very strong gust of wind to blow out the candle. Even if it's a 1.5V or 3V motor, hitting it with 5V for a second will cause no harm to the motor, but ought to extinguish the flame, assuming the fan is in front of it.
(Psssssst: Hey Chip: You're getting tips from the Master: Gordon is a bestselling author of more than 65 books and thousands of magazine articles.)
We're all GMc fanboys here.
I have had experience with electronics, so this should not be too much trouble. I have actually put 3 volts to the motor and it spun fast enough to extinguish the candle.
Relay needs 5V, which may as well be your fan voltage too. Provides complete isolation between micro and switched power, you could control some big stuff with this setup.
I wonder if they have any DPDT relays? Would be handy for motor control.
If it doesn't need to run for long then why not have a large capacitor always charging and run the motor off it when needed.
Totally agree, but have only ever seen SPDT relays on these cheapie 5V modules, anyway. Good enough for on/off in this application.
Look at one of Erco's infamous flamethrowers which use a servo to press down the button of an aerosol can.
You could use a can of air as a fire extinguisher.
For a candle flame, an air cannon can giveth life, and also taketh away.
There's a thought. If I can't get the motor to work, I might be able to try that. Thanks!
Well, I got a suggestion from my dad about how to throw the smoke ring. Have a servo push a spring-loaded rod down and when the servo arm goes past the point of the rod that's being pressed, then it should fly up and hit the elastic covering for the cannon, therefore making a torroidal vortex.
If this project follows the basic Trinity robotic fire fighting rules, you get extra points for using a small CO2 canister or other non-air means of extinguishing the candle. Water works too. The rules book points out fighting fires with air isn't really practical in the real world, and they reward robots that use a more realistic approach.
I actually got the inspiration to do this from a Servo magazine. There was an article about this that said almost exactly the same thing you said. I just decided to use air to do this which is why I posted this discussion about not being able to get a motor to spin. I don't know if I said this before, but I'm doing this for a 4-H project.