Hello!

I'm trying to control a step by step motor with my arduino Uno. I added a ULN2003a between them to have more current in my motor.
I wanted to test the ULN2003a a bit before I use it on my motor. I made a little circuit with a switch and a LED. (picture joined)
But the ULN2003a is not responding as I was expecting. The tension between A and B is -0.5 V without the switch OFF and
4.4 V when it's ON. The LED is not on. (I tested it, everything except the ULN2003a works).

Is the chip dead?
Or have I made a mistake?

Thank you for your help!

Christian

 

You have made a mistake, the chip acts like a switch to ground, so at minimum the LED is backwards and should go to the +5 volts.

When I get to my pc I will check a few more things I can't see on my iPad.

Edit: That should be it. I doubt your mis connections damaged your part.

View attachment 97676

 

You cannot use the part to source current into a grounded load.
Check the functional block diagrams on p.12 of the following

http://www.ti.com/lit/ds/symlink/uln2003a.pdf

 

I understand now! It works! Thank you all!