Print PDF
Favorite
Email
Step 9The H-bridge
The first picture is a simplified H-bridge. The motor in the center is connected to 9 volts of power and ground by four switches (S1, S2, S3, and S4). With all four switches off, the motor will not get any power and the motor will not turn. The switches can be turned on in pairs: S1 and S4 or S3 and S2 to allow current to pass from the 9 volt batteries through the motor to negative or ground.
Now take a look at the second picture.
If you close switches S1 and S4, current will flow through the motor and it will turn in one direction.
If you close switches S3 and S2, current will flow through the motor and it will turn in the opposite direction.
The H-bridge is a very simple circuit. Unfortunately it would be impractical to use manual switches to drive a motor. Several companies make H-bridge integrated circuits (ICs) that are easy to use by simply applying power to a particular pin also called "setting the pin high" to drive the motor in one direction. Cutting the power to that pin and applying power to another pin will drive the motor in the opposite direction. The circuitry inside the H-bridge ICs is somewhat complicated, so most folks will choose to use an H-bridge IC rather than building the circuit themselves.
The third picture is the Snap Circuits Motor Control IC, or H-bridge. At the top of the figure you can see the electronic schematic of the Motor Control block. On the lower left you can see a picture of the block. The lower center shows the function of each snap for the block and on the lower right is a description of what each snap does.
Now take a look at the second picture.
If you close switches S1 and S4, current will flow through the motor and it will turn in one direction.
If you close switches S3 and S2, current will flow through the motor and it will turn in the opposite direction.
The H-bridge is a very simple circuit. Unfortunately it would be impractical to use manual switches to drive a motor. Several companies make H-bridge integrated circuits (ICs) that are easy to use by simply applying power to a particular pin also called "setting the pin high" to drive the motor in one direction. Cutting the power to that pin and applying power to another pin will drive the motor in the opposite direction. The circuitry inside the H-bridge ICs is somewhat complicated, so most folks will choose to use an H-bridge IC rather than building the circuit themselves.
The third picture is the Snap Circuits Motor Control IC, or H-bridge. At the top of the figure you can see the electronic schematic of the Motor Control block. On the lower left you can see a picture of the block. The lower center shows the function of each snap for the block and on the lower right is a description of what each snap does.
| « Previous Step | Download PDFView All Steps | Next Step » |
 |
Add Comment
|
