I am looking for some help with a circuit to reverse a DC motor when it's current reaches a certain level. I think that current level will be in the neighborhood of 2A, however I would like this to be adjustable.
I have a 9V DC motor that is going to be winding up some cable. I'd like to have the motor reverse direction when the cable gets tight, and then continue running in the reverse direction until it gets tight again and then reverse and so on.
I am thinking the best way to do this is to monitor the current to the motor by measuring the voltage across a low-side sense resistor, and then have the circuit flip a latching DPDT relay to reverse the motor.
Here is what I have come up with so far; http://www.skot9000.com/proj/wiremotor/circuit1.pdf
Does this seem reasonable? Any part suggestions for the opamp and comparator? I don't really have any experience designing analog circuits. I have read about hysteresis and it sounds like I will need it on the comparator.
Also, where do people get high wattage non-wirewound 0.1ohm resistors?
thanks!
-Skot
I have a 9V DC motor that is going to be winding up some cable. I'd like to have the motor reverse direction when the cable gets tight, and then continue running in the reverse direction until it gets tight again and then reverse and so on.
I am thinking the best way to do this is to monitor the current to the motor by measuring the voltage across a low-side sense resistor, and then have the circuit flip a latching DPDT relay to reverse the motor.
Here is what I have come up with so far; http://www.skot9000.com/proj/wiremotor/circuit1.pdf
Does this seem reasonable? Any part suggestions for the opamp and comparator? I don't really have any experience designing analog circuits. I have read about hysteresis and it sounds like I will need it on the comparator.
Also, where do people get high wattage non-wirewound 0.1ohm resistors?
thanks!
-Skot