arduino & simple motor

Forum 2005-2010 (read only) Hardware Interfacing
1

Hello everyone,

I am new to arduino and electronics. So, first of all sorry for the basic question :wink:

I am trying to control a simple 5V motor with the following schema:
[URL in 1st answer to this post]
(the transistor is a 2N2222A and the diode iN4004)

Since it did not work, trying to figure out what was wrong, I removed the motor from that circuit and measure the voltage in the corresponding part: It was OK, and it moves ON (5V) and OFF (0V) responding to the value of the digital pin. But when I connected the motor back, the voltage in the same points become 10 times smaller (0.44 V aprox, not enough for driving the motor), although it also went ON and OFF depending on the digital pin value. What is wrong? Why connecting the motor reduces the voltage? Any help would be appreciated.

By the way, the motor is a "reduced" one (I do not know whether that is the right word in English): I mean it has a lot of gears to spin at a very low speed but with high torque. I do not know whether that has anything to do with the problem.

Thanks a lot in advance!

Regards,

2

That is the URL with the schema. I was not allowed to include it in my first post:

3

Using that circuit you are only ever going to get 5V on the motor, that is what is called an emitter follow. The fact you get even less suggests that there is not much current gain in that transistor.

You need to have voltage gain so connect the emitter to ground, one end of the motor to the collector and the other end of the motor to the +9v. Then reduce that base resistor to 1K.

4

Hi Mike,

It works now! Thanks a lot for your help!!

Cheers,