![]() ![]() I believe I found the range to be limited, or tricky to get right. I did use a digital pot in place of the analog pot. I built a circuit like that once to control fan speed. Ill attach a similar circuit that i think it is but im not sure.Īny one know how can i replace or control this I did a little more searching and discovered that there is a 555 ic timer for the pwm to the transistors. The two wires red and black are an on off switch The group of three wires makes sense, the red and black are a mystery to me. If that really is a double stacked pot you are going to have trouble replacing the pot with an Arduino without understanding why there are two pots. Is there a switch built into the pot? You already have a on off switch. The red and black wires from the pot are not making sense to me. I don't understand why the motor controller uses a double stacked pot. ![]() Switching noise will effect the Arduino, and maybe even kill it. I would recommend using a separate power supply for the motor controller. I assume that the red board shown in your rough schematic is a DAC, which feeds the opamp. The motor is connected to a 5V power supply whose ground is shared with Arduino ground.Sorry no idea what a digital pot is but will google it now A noise filtering 0.1uF decoupling capcacitor and protection diode 1N4001 from possible back emf voltage spike from the motor are connected across the motor. The DC motor is connected to the transistor collected. A 10KOhm is also connected from the base of the transistor to ground to reduce chances of accidental signal into the sensitive base of the transistor. ![]() The PWM pin 10 of Arduino is connected to a 2N2222 transistor via 1KOhm resistor. Here we have connected a 10KOhm potentiometer to the analog pin A0 of Arduino with the other two ends to 5V and ground. Wiring diagram for Potentiometer Controlled DC motor control using PWM of Arduinoīelow you can see the schematic diagram used to control the DC motor speed using potentiometer controlled PWM signal from Arduino. The mapping is simple and we just have to divide by 4. Once quantization value is collected during one sample time, the value can be mapped to corresponding PWM level which can be from 0 to 255 because PWM is defined by 8-bit resolution and 2^8 = 256 and again taking 0 as count start the PWM level is from 0 to 255.īy mapping the ADC value range 0 to 1023 to PWM levels 0 to 255 we can then send the analog value collected to the PWM level converted value to the PWM pin. The quantization level of 0 corresponds to 0V and 1023 corresponds to 5V. These level values called quantization level from 0 to maximum of 1023 is due to the fact that arduino ADC has 10-bit resolution which gives 2^10 = 1024 quantization level but since count starts from 0 the level is from 0 to 1023. We then read in the analog signal samples using Arduino ADC and convert it to quantization level value between 0 to 1023. To use potentiometer to control speed, we connect potentiometer to the analog input pin of the Arduino. In this way PWM is used to control the speed of a motor. The more energy/power is delivered to the motor the faster it will rotate. The more time the pulse stays high the more energy or power is delivered to the motor. If for example, we have a PWM signal with 75% high and 25% low it means that in the total period the pulse stays high for 75% of the time and 25% of the time. By controlling how long the pulse stays high and low during a period we can control how much energy(or power) is delivered to the motor. Duty cycle is the ratio of how long the signal stays high to the total pulse period. PWM is a technique of generating High/Low pulse of different duty cylce. Pulse Width modulation(PWM) with Potentiometer & Arduino
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