The following article will describe you with how to stabilize DC motor’s speed using ZTX450 NPN silicon planar transistors in bridge circuit. The circuit description is to improve the load/speed regulation of a DC motor by cancelling out the effect of the motor rotor resistance using a bridge circuit.
The circuit diagram above illustrates the DC motor speed control circuit with the bridge circuit within. You will find detail explanation about the theory in how to calculate and measure the motor resistance, the current/speed and torque/speed characteristics, and a proof analysis which shows that the speed is not directly dependent on the motor current.
See detailed explanation of How to Stabilize DC Motor’s Speed using ZTX450 NPN Silicon Planar in Bridge Circuit in this diy DC motor article, 3 pages/118 Kb pdf filetype (source: diodes.com).
