All,
I'm a complete newb here and a mechanical engineer to boot. I have played with Arduino when I built a 3D printer but had to follow detailed instructions to make it work. Fast forward a couple years and I have decided I want to use an arduino to build a fixture for some life cycle testing.
I'm sure this is as simple as it gets, but I have been unable to find enough information to be able to do what I need to do.
I have a very simple pcb. When a switch is pushed a motor starts and when it's released the motor stops.This switch is carrying very little (-4.5v) current. The switch is connects the ground signal to the motor.
I would like eliminate the switch and automate this connection this an Arduino Uno board I have. Can I just hardware these two wires somewhere or do I need to add relay to make the connection? Basically I just want to make the connection for some number of seconds and then disconnect it for some number of seconds. I think I can figure it out once I know where to start.
Thanks in Advance!
David
cepdave:
All,
I'm a complete newb here and a mechanical engineer to boot. I have played with Arduino when I built a 3D printer but had to follow detailed instructions to make it work. Fast forward a couple years and I have decided I want to use an arduino to build a fixture for some life cycle testing.
I'm sure this is as simple as it gets, but I have been unable to find enough information to be able to do what I need to do.
I have a very simple pcb. When a switch is pushed a motor starts and when it's released the motor stops.This switch is carrying very little (-4.5v) current. The switch is connects the ground signal to the motor.
I would like eliminate the switch and automate this connection this an Arduino Uno board I have. Can I just hardware these two wires somewhere or do I need to add relay to make the connection? Basically I just want to make the connection for some number of seconds and then disconnect it for some number of seconds. I think I can figure it out once I know where to start.
Thanks in Advance!
David
Relay shields are widely available and fairly cheap, you may wish to look into them.
An Arduino Uno is rated at 40mA max. Even small pager motors are likely to draw more than that. So, you will need a relay, and since the relay will probably draw more than 40mA itself, you will need a transistor to switch it.
So, you have options.
Drive the motor through a transistor or FET switch. Since the load is inductive you may need a snubber or a diode across the motor. Bipolar transitors will need a resistor in series with the base, a few k ohms
Use a small transistor or optoisolator to drive the relay. And maybe a resistor or two and a cap.
Or buy a shield with all the parts already figured out.
Switched inductive loads can let the smoke out of your parts in a hurry. I've fried a few and was even in the ballpark with the calculations.
LOL... I think I just figured out how a transistor works. Going to give it a shot on my own. 