Motor powered externally by 9V battery Pulsing

I’ve attached a photo of the wiring. The motor only has to spin one way for a short period of time. The circuit works when powered by AAs but they weren’t making the motor spin fast enough to launch the rack in a rack and pinion mechanism. However, with the 9v battery, the motor pulses when it should be written low. and doesn’t seem to increase the speed of the motor when it’s written high.

Please help

You have said nothing about the motor specification, the other components or the type of battery and unfortunately the picture shows nothing very useful. A circuit diagram would be a lot more helpful.

So for now I'm going to guess that you're using a little rectangular MN1604/PP3 9V battery which can't supply enough current for your motor. Try it with 6 x AA batteries and see what happens.


A 2k2 base resistor driving an unknown TO-92 transistor... Must be a tiny motor. Give us all the information, so we don't have to guess. Leo..

Firstly something must be wrong with the circuit or transistor if the motor runs with the output low, did you double-check the pinout? Is the transistor rated for the max current? Does it have enough switching gain for a 2k2 base resistor (the answer will be no unless its a darlington).

But most fundamentally a small 9V battery isn't really able to source enough current for a small motor...