# Help with my Project, Digital Input Motor Control

#### Thevenin99

Joined Mar 23, 2017
12
Hi everyone

I am trying to understand how to do my assignment, it is a motor that will be controlled with pulse-width modulation and the current is switched by power transistors. The way I think we can do this is with an H bridge by having 4 mosfets, 2 pmos and 2 nmos and having a circuit like the one in the picture.

We need to have a MUX with 2 inputs , A and B that will follow the requirements that when both A and B are ON, the motor will run at 100%, when A is 0 and B is 1 it will run at 30%. One of my problems is that Im not familiar with pulse width modulation, I don't know how to implement it to the MUX.

The power supply +12 volts and -12 volts.

We cannot use any sort of microcontrollers so I think the MUX should be constructed out of discrete components.

My biggest question is how to construct the H bridge such that it is connected to the MUX, how to make them work together

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#### StayatHomeElectronics

Joined Sep 25, 2008
1,020
Are you being supplied the various PWM signals?

Can you explain how a MUX operates?

#### Thevenin99

Joined Mar 23, 2017
12
Are you being supplied the various PWM signals?

Can you explain how a MUX operates?
the pulse frequency is 1.2khz+/-100 hz

For the Mux we have three bits, abc and the inputs accpt voltages from 0 to 0.8v as low and any voltage from 3 to 5v as high

#### StayatHomeElectronics

Joined Sep 25, 2008
1,020
What does the MUX do with the inputs?

Did you research what pulse width modulation is? You must generate the PWM signal from a 1.2 kHz clock. Any other signals supplied in the problem?

30% refers to the percentage of time the signal is HIGH in the PWM SIGNAL.