# Need Help with Amplifier

Discussion in 'The Projects Forum' started by Mr.CiviC, Dec 21, 2011.

1. ### Mr.CiviC Thread Starter New Member

Oct 27, 2010
9
0
Hello everyone,

Im working in a project that I need to drive to motors.
I'm using Arduino Microcontroller. My problem is that the microcontroller output is 0~5V. But I want to drive the motor with more voltage to get better performance. So, can you guys help me to find a circuit for amplifier or IC that may help me to do that. I want to drive my motor with 0~ 9V. Thanks.

2. ### Wendy Moderator

Mar 24, 2008
20,772
2,540
Are you familiar with PWM? A simple transistor (if it is a MOSFET it will need to be a logic level) will do it.

3. ### Mr.CiviC Thread Starter New Member

Oct 27, 2010
9
0
Thanx Bill for replying.
I know amplifiers are made of transestor but I need help of designing an amplifier.
I have seen many Amplifiers circuits but what I dont know is the gain How can I design amplifier with gain equal to what I want ( 0~5V) to ( 0~ 10V)

4. ### Wendy Moderator

Mar 24, 2008
20,772
2,540
Basically it is the power supply. The pic can use the 5V, the LED/transistor/resistor is connected to 9V.

5. ### Mr.CiviC Thread Starter New Member

Oct 27, 2010
9
0
I think you didnt get my point. I want to control the speed of the motor with the microcontroller ( Im using Arduino ). Well arduino output is 0~5V but i want to amplify it to 0~10V.

6. ### SgtWookie Expert

Jul 17, 2007
22,183
1,728
PWM is short for "Pulse Width Modulation".
In PWM, you usually have a fixed frequency or pulse repetition time, and the ON time to OFF time of the pulse is adjusted from 0% to 100%, and everywhere in between.

PWM is far more efficient than linear regulation, as the power switch is either ON or OFF instead of a partially conducting aka resistive state. With PWM, practically no power is dissipated in the switch. With linear regulation, the power losses in the controlling device can be staggering.

In PWM, the power is turned on and off very rapidly, hundreds of times to thousands of times per second. Since the amount of time the current flows through the motor can be controlled, the power used in the motor is also controlled. It winds up having the same effect as a linear regulator, without the associated power losses. This is why PWM is so prevalent nowadays.

7. ### thatoneguy AAC Fanatic!

Feb 19, 2009
6,357
718
How much current do your motors draw?

What you are looking for is called an H-Bridge driver IC.

some have the MOSFET H-Bridge Built in, some don't.

They have two supply voltages, one that is uC level/logic level, and the other is motor supply voltage (6-24V typ)

Then there are essentially 3 wires that control the motor, for forward, backward, brake, and coast.

An example of this is the L293D (click for datasheet)