My question is this - Do I need a resistor in a circuit with a 9v battery connected to a 3.7v 200mA Motor because when I tried it without a resistor it got hot very quickly? In another thread a member said that I do not need a resistor for it as the motor will do it itself? Does this mean that I should change the voltage instead of current?

Thanks. (I am very new to this so my question will seem simple to many of you I imagine so please bear that in mind when explaining it to me!)

 

The voltage is the force and the current is the food for the circuit. Consider the following ...

A tap with running water. The pressure behind the water is the voltage and the actual water is the current.

You do not want an resistor for your motor to drop the current. What you want is either an
9 volt motor or an PWM circuit to control your existing motor.

 

Does this mean that I should change the voltage instead of current?

Yes, the supply voltage needs to match the motor voltage. You could change the battery from a 9V to a pair of 1.5V AA, AAA, C, or D cells in series, all of which wold give much longer life than the 9V.

 

What you want is either an
9 volt motor or an PWM circuit to control your existing motor.

Thanks for the help! How would I wire a PWM into the circuit as it has 3 pins - I presume 2 will be for +/- but what will the other be connected to?

 

If I had something like this instead of setting it up myself, would it work? http://www.amazon.co.uk/Motor-Contr...407680817&sr=8-3&keywords=9v+regulator+module

 

If I had something like this instead of setting it up myself, would it work? http://www.amazon.co.uk/Motor-Contr...407680817&sr=8-3&keywords=9v+regulator+module

Yes. Cheaper you buy existing product. But be carful not to turn the speed up all the way since the supply is 9 volt and the motor is only 3 volt.