I just hacked an Epson C80 printer to get the motors to learn how to drive them. There is a Stepper for the paper advance and a 2 wire dc motor for the inkjet carriage. These were actualy driven by 35v and 45v. I want to learn how to drive these and have been reading the archives.
For the 2 Wire DC motor. The winding resistance is 23.8 ohms. If I try to run this at the TTL level I get 5/3.8= 210 mA current. I undersand that the max curent the pins can handle is 20 mA. So I assume I need to put in a Power Resistor in series to reduce the current? 5V/.02A = 250 ohms. Minus the 23.8 give me about a 220 ohm resistor. The power would be 5v*.02A = .1W
Will this work? How do I determine if I need put the resistor on the ground or +5v side?
As for the Stepper Motor.
It is a 4 wire bipolar motor. There is 3 ohms between each winding. 5V/3ohm = 1.66 amps. Using the same logic would I need a 248.33 resistor in each leg to be able to drive it directly with the output pins?
Power would also be 0.1 W
Are these assumptions correct?
Thanks for the help
Steve
For the 2 Wire DC motor. The winding resistance is 23.8 ohms. If I try to run this at the TTL level I get 5/3.8= 210 mA current. I undersand that the max curent the pins can handle is 20 mA. So I assume I need to put in a Power Resistor in series to reduce the current? 5V/.02A = 250 ohms. Minus the 23.8 give me about a 220 ohm resistor. The power would be 5v*.02A = .1W
Will this work? How do I determine if I need put the resistor on the ground or +5v side?
As for the Stepper Motor.
It is a 4 wire bipolar motor. There is 3 ohms between each winding. 5V/3ohm = 1.66 amps. Using the same logic would I need a 248.33 resistor in each leg to be able to drive it directly with the output pins?
Power would also be 0.1 W
Are these assumptions correct?
Thanks for the help
Steve