This my first electronics project and it is based on this project.
I'm using a TI SN754410NE H-Bridge to control 2 small dc motors. I'm using an Arduino UNO for the control signals (USB powered) and a 6 V battery supply to power the motors. The battery supply negative is connected to Arduino GND.
It is actually working but there is something a bit unusual. When I measure the voltages being supplied to the 2 motors I get voltages for one motor of +/-4 V but for the second motor it is 3 V in one direction and -4 V in the other. I have checked all the connections and they are fine. Also, is it to be expected to get a significant voltage drop when using this type of device (h-bridge) ? I was naively expecting to get 6 V.