Connecting an L293D H-Bridge to a DC Motor: Advice Needed

In summary, the person is seeking advice on connecting a L293D H-Bridge to a 12V DC motor using a PIC 16F877A microcontroller with a 5V output. They are unsure if they can use a breadboard with a 15V rail and a ground rail for this setup and have studied the data sheet but are still confused. The expert's response is that they can connect the H bridge to the 15V and ground rail, but to limit the PWM-signal to ±12V and note the bridge's limit of 36V.
  • #1
axe34
38
0
Hello

I was wondering if you could advise me on the following. I am undertaking a personal project at home (mainly mechanical in nature) whereby I require the L293D H-Bridge to connect to a 12 V DC motor. I'm using a PIC 16F877A microcontroller. This microcontroller has a 5V output. The breadboard I have has a 15V but no 12 V rail.
Can I connect the H bridge to the 15V rail and ground rail? Will the DC motor work ok?
I have studied the data sheet but I'm still confused!Thankyou
 
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  • #2
axe34 said:
Can I connect the H bridge to the 15V rail and ground rail? Will the DC motor work ok?
Yes, just limit the PWM-signal to yield ±12V ( ±80% duty cycles ).

The limit as for the bridge itself is 36V.
 

1. How do I connect an L293D H-Bridge to a DC motor?

To connect an L293D H-Bridge to a DC motor, you will need to first identify the input pins of the H-Bridge. The pins will be labeled as "1", "2", "3", and "4". Connect the positive terminal of the DC motor to pin 3 and the negative terminal to pin 4. Then, connect the power supply (usually a battery) to pins 1 and 2, with the positive terminal to pin 1 and the negative terminal to pin 2. Finally, connect the control pins of the H-Bridge to a microcontroller or other control circuit to control the direction and speed of the motor.

2. What is the purpose of using an H-Bridge with a DC motor?

An H-Bridge is used with a DC motor to allow for bidirectional control of the motor. It allows the motor to be driven in both forward and reverse directions, as well as varying the speed of the motor.

3. Can I use any DC motor with an L293D H-Bridge?

Yes, you can use any DC motor with an L293D H-Bridge as long as the motor's voltage and current requirements are within the specifications of the H-Bridge. The L293D is typically rated for motors with a voltage range of 4.5V to 36V and a current capability of up to 600mA.

4. What precautions should I take when connecting an H-Bridge to a DC motor?

When connecting an H-Bridge to a DC motor, make sure to double-check the polarity of the connections to avoid damaging the components. It is also important to ensure that the power supply used can provide enough current to drive the motor, as the H-Bridge itself does not provide any amplification. Additionally, it is recommended to use flyback diodes to protect the H-Bridge from voltage spikes generated by the motor.

5. How can I control the speed of a DC motor using an H-Bridge?

The speed of a DC motor can be controlled by varying the voltage applied to the motor. This can be achieved by using pulse-width modulation (PWM) signals from a microcontroller or other control circuit, which will turn the motor on and off rapidly to simulate a lower average voltage. The duty cycle of the PWM signal can be adjusted to control the speed of the motor.

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