Have problems while testing the motor driver on the breadboard for my project

5 years 11 months ago #29533500 by Wuchan
I want to build a robotic arm for a project, but I got stuck while testing the motor driver on the breadboard.

I have followed the instructions from this instructable: www.instructables.com/id/Easy-DC-Motor-Controller/ and I connected the pnp transistors(what's pnp transistor: www.apogeeweb.net/article/72.html ) the right way (the author confirmed in the commentaries a long time ago) and also like in the diagram.

The problem is that when I turn the power on, the motor starts to spin (slowly but it has a snail gearing reducer) and the first mosfet is getting very hot very quickly, and if I try to control the circuit by touching the first contact with a positive voltage it doesn't do a thing. I even tried doing only half of it.

I tried to reassemble it again many times, changed the transistors with other new ones, checked the connections and after numerous voltage measurements I concluded that the problem is that, when I am powering up the circuit, for some reason, there is a 12v voltage between the pnp collector and ground and the voltage continues all the way to the resistor to the far left, although at the resistor the voltage is dropped to about 7v.

I also simulated the circuit in proteus before i bought the parts (I need 6 good working drivers) and it worked fine.

It may be a stupid mistake, but please help me if you have any idea what the problem might be!

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5 years 11 months ago #29533502 by Gabriel_Isko
I'm not sure what is going on in your circuit, but if you are looking for a simple brushed DC motor driver, I would recommend taking a look at our Brushed DC Motor Controllers .

Good luck with your robot arm! It sounds like a cool project.

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