So, I have been long struggling with getting a L298 motor driver I have to work. I figured it to be more compact than wiring up all the protective diodes myself so I purchased this: Where the board simply supplies a regulator, protection diodes, and a filter capacitor. Anyway, I have gotten the chip to work fine at higher voltages. My problem lies here in the actual schematic of the H-Bridge: By setting IN1 HIGH, IN2 LOW, and ENA HIGH, the motor will conduct via the top left and bottom right transistors. Now, my problem is that my motor is of the 3V variety. Initially, I had a problem with the driver not turning the motor at all. It turned out that my supply VS (~3V at the time) was insufficient because a significant voltage was being dropped across the transistors. So, after upping VS to 4.6V (3 D-cell batteries) the motor would turn fine. However, now, after measuring, the voltage at the motors terminals are 3.3V and 0.8V. And my questions are: *How to calculate the voltage across a DC motor in general? *How to calculate the voltage drop across the transistors in the H-Bridge circuit to determine the voltage at the motor leads? *In my case, is the 2.5V seen across the motor demanded by the current through its coil, or a product of the current through the transistors? --It seems that the current through a coil (V = L di/dt) would be zero for a DC motor. Why am I measuring 2.5V? Can this be entirely attributed to the internal resistance of the wires? Does this affect the motor in any way? --The datasheet for my motor states that at no load a 300mA current is drawn. So, are my measurements going as far to say there exists a 8 Ohm internal resistance? So, at higher currents, the drop across the motor should get larger? What if the current is such that (assuming the motor were to not burn up at this point) the voltage demanded across the motor was 5V or so (~0.625A current given 8 ohm internal resistance) .. would the motor at some point between 2.5V and 5V simply shut off and "open" the circuit path? Or it seems that perhaps the current would demand a larger voltage drop across the transistors - but with sufficient current would the motor still turn despite lowered voltage across its terminals? Then we are right back the first and second questions.