Control a Motor with PWM Using the 555
DC motor control with 555
This simple circuit, running on 12 volts, allows control of a DC motor with the 555 timer. The design began with the idea of using a power MOSTET transistor to control the motor, but in the end a bipolar transistor was chosen.
To vary the speed of the DC motor, the 555 timer that works as a PWM (Pulse Width Modulator) was used. Variation is achieved by manipulating potentiometer P.
The output of the 555 activates the set of transistors in cascade Q1 and Q2 that govern the DC motor. The type of motor to use is 12 volts and the current is limited to the capacity of the output transistor.
DC Motor Control Operation with 555
The operation of the 555 is very similar to its operation in astable configuration, with the additional feature that the width of the pulse at the 555 output (pin3) can be modified.
This is accomplished with the arrangement of the diodes (D1, D2), the resistors (R1, R2), the potentiometer P, and the capacitor C1.
The purpose of this group of components is to regulate the charge and discharge times of capacitor C1 and thus establish the time that the 555 has its output high and low. Since the output of the 555 is of the square wave type, the motor will have 12V (or a little less) between its terminals for a while and 0V (or a few millivolts) for another time.
555 Timer Internal Configuration and Pinout
The longer the 555 output is high, the longer the Q1 and Q2 transistors will be saturated and as a consequence the longer the DC motor will be with 12 volts across its terminals.
Conversely, if the output of the 555 is low for longer, transistors Q1 and Q2 will be cut off for longer and as a consequence the motor will spend less time with 12 volts between its terminals.
Control a Motor with PWM Using the 555
DC motor control with 555
This simple circuit, running on 12 volts, allows control of a DC motor with the 555 timer. The design began with the idea of using a power MOSTET transistor to control the motor, but in the end a bipolar transistor was chosen.
To vary the speed of the DC motor, the 555 timer that works as a PWM (Pulse Width Modulator) was used. Variation is achieved by manipulating potentiometer P.
The output of the 555 activates the set of transistors in cascade Q1 and Q2 that govern the DC motor. The type of motor to use is 12 volts and the current is limited to the capacity of the output transistor.
DC Motor Control Operation with 555
The operation of the 555 is very similar to its operation in astable configuration, with the additional feature that the width of the pulse at the 555 output (pin3) can be modified.
This is accomplished with the arrangement of the diodes (D1, D2), the resistors (R1, R2), the potentiometer P, and the capacitor C1.
The purpose of this group of components is to regulate the charge and discharge times of capacitor C1 and thus establish the time that the 555 has its output high and low. Since the output of the 555 is of the square wave type, the motor will have 12V (or a little less) between its terminals for a while and 0V (or a few millivolts) for another time.
555 Timer Internal Configuration and Pinout
The longer the 555 output is high, the longer the Q1 and Q2 transistors will be saturated and as a consequence the longer the DC motor will be with 12 volts across its terminals.
Conversely, if the output of the 555 is low for longer, transistors Q1 and Q2 will be cut off for longer and as a consequence the motor will spend less time with 12 volts between its terminals.
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