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GarciaATlab5Lab 5: 555 Timer Applications Part A 1.PWM is Pulse Width Modulation. PWM allows a change in how frequency energy is pulsed to decrease speed of a motor (or other device) while still maintaining the same amount of power(wave form of duty cycle). PWM is useful because the same power source can be used while a motor is operated and the motor can move at different speeds with the same power by changing the PWM. 2. Please see handout 3.Rb1+Rb2=100k ohms 4.An astable circuit would send one pulse when triggered. Although the on time of the pulse can be changed by rotating the potentiometer, the duty cycle would not change. Diodes are necessary to provide one path for the current to follow. On time: 7 ms Off time: 7ms Period: 3.9 ms 5.see above 6. I think that PWM would be more effective with a longer period because there is plenty of time for the exchange between on time and off time. When the period is shorter, the on time and off time switch at a much faster rate, causing inefficiency. This could be checked using a multimeter and making sure the voltage drops to zero and increases to the full voltage. This can be done at the short and the long period and the one that does not change from the high voltage number to zero is not as effective. 7.MOSFET is a metal–oxide–semiconductor field-effect transistor which is used to either amplify a signal or switch a signal. In this circuit, the device is needed so that a large current can flow through and a small input signal to result in a large change in current output. |