Help - Shaking ground !!!

[dreamproject]

Hi everyone,

I have a rather strange (could be dumb :wink: ) problem . My project is constructed such that an input from a sensor ( pot) drives a stepper(angle). The basic flow of data is :

POT --- ADC (0809) --- PC--- DIVER IC's (uln 2003) --- STEPPER.

Since my inputs and outputs are interfaced by the same parallel port . It is required that all grounds be connected together . But since the input and output (driver) circuits run at different voltages (5v and 12 v), the stepper circuit seems to be sinking some current to the input circuit , causing the ADC to heat up. The circuits work fine individually ,

Thanks to anyone who can provide relief to this head- ache of mine and sorry for the long post.

 

[bmcculla]

One thing that is a good idea to do is to use separate wires for the different devices. So the stepper and ADC have separate ground wires that all connect together at one point. This keeps current from the stepper from flowing past a ground connection used by the ADC.

Make sure that the input voltage going to the ADC doesn't exceed its input voltage.

 

[Nigel Goodwin]

It is required that all grounds be connected together . But since the input and output (driver) circuits run at different voltages (5v and 12 v), the stepper circuit seems to be sinking some current to the input circuit , causing the ADC to heat up. The circuits work fine individually ,

If the grounds are connected correctly there should be no problem at all, it sounds like you have something connected wrong somewhere - perhaps you might post the circuit for us to check?. However, it could also be in the way you've wired it!.