how can I control a stepper with an encoder?

[NASR1]

Hi all
I need to be able to contol a motor simply by turning an encoder shaft and have the motor respond in position, velocity, and direction accordingly.I need a schmatic of stepper controller with an encoder.
I find about this subject in internet. http://www.webx.dk/oz2cpu/20m.htm
how to connected this circuit with stepper controller.?

thank you any advice would be nice.
nasr1.

[nophead00]

I think that is a circuit to use a stepper as a shaft encoder. It looks like it produces two outputs which will be square waves 90 degrees out of phase with each other as the stepper is rotated.

[nophead00]

To drive a bipolar stepper you would simply need to amplify the two signals to provide sufficient voltage and current for the coils. To drive a unipolar stepper you would need a couple of inverters to make the four signals before using a drive chip to amplify them.

[NASR1]

Originally Posted by nophead00 To drive a bipolar stepper you would simply need to amplify the two signals to provide sufficient voltage and current for the coils. To drive a unipolar stepper you would need a couple of inverters to make the four signals before using a drive chip to amplify them.

Thank you for response.

how to connected this circuit with stepper controller.?

Do you have a schmatic of stepper controller with an encoder.?

[nophead00]

Sorry I don't have a schematic. You don't need a stepper controller with this scheme, just a driver chip. The type of driver chip would depend on the specification of your motor. As a simple example to drive a small uniploar 12v motor up to 0.5A per winding you could use something like a ULN2803. It has 8 darlington drivers and you can connect them in parallel in pairs to make four higher current channels. You could take the A and B outputs of your example circuit and invert them with somthing like a 74HC04 to make A-INV and B-INV. Feed those four signals into the 2803 and connect the outputs to a unipolar motor. These have two center tapped coils. Connect the taps to 12V. Make sure connect the outputs correspoing to A and A-INV to one coil and B and B_INV to the other.

Connect a small stepper with the same number of steps J1. When you turn it the output stepper will follow provided you don't go very slowly or too fast.