Controlling supply voltage with aruino

Other Hardware General Electronics
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Hi! Last week i posted a question about controlling the speed of a water pump with PWM. I was told the reason it doesn't work is because the motor is a brushless DC motor and can't be controlled by PWM on the supply voltage. I noticed i can control the speed by increasing/decreasing the voltage from my bench power supply.

My question then is:
Is there some circuit or component i can buy that allows me to supply it with 12V, and that i can use an arduino to control the voltage output? (And is a constant output and not generated with pwm) And also is capable of delivering around 0.2A.

Thanks in advance!

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A cct. like this will work, see the data sheet for the LM117, LM317-NWideTemperatureThree-PinAdjustableRegulator

Figure 34
https://www.ti.com/lit/ds/symlink/lm117.pdf

You could probably do the same with a ‘buck converter’.

Make sure there is a max output voltage setting resistor.

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larryd:
A cct. like this will work, see the data sheet for the LM117, LM317-NWideTemperatureThree-PinAdjustableRegulator

Figure 34
https://www.ti.com/lit/ds/symlink/lm117.pdf

Awesome! Thank you!

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larryd:
A cct. like this will work, see the data sheet for the LM117, LM317-NWideTemperatureThree-PinAdjustableRegulator

Figure 34
https://www.ti.com/lit/ds/symlink/lm117.pdf

You could probably do the same with a ‘buck converter’.

Make sure there is a max output voltage setting resistor.

If i use this component, am i only able to use a set amount of ouput voltages depending on how many different resistors i connect? Or am i misunderstanding? (my knowlege is very basic).
What i'm after is a stepless conversion of a pwm signal (or other method) to a stable voltage.

5

Yes there will steps in the voltage controls, 24 = 16.

If you use 5 transistors, 25 = 32.

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larryd:
Yes there will steps in the voltage controls, 24 = 16.

If you use 5 transistors, 25 = 32.

Ok thank you, i will try this!

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You CAN use PWM - you just need to smooth it out with a simple rc filter so the signal looks like a dc average.

Feed it to the base of a suitable NPN transistor, with the motor in the collector circuit.

You can even put another cap across the motor for even more smoothing.

That will give you smooth & progressive control.

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johnerrington:
You CAN use PWM - you just need to smooth it out with a simple rc filter so the signal looks like a dc average.

Feed it to the base of a suitable NPN transistor, with the motor in the collector circuit.

You can even put another cap across the motor for even more smoothing.

That will give you smooth & progressive control.

wow thanks! that sounds much simpler, i will read about this and see if i can figure it out.

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I was told the reason it doesn't work is because the motor is a brushless DC motor and can't be controlled by PWM

Is that really true? I'm thinking it should work as long as you have a motor driver circuit...

What are you using for a driver? Can we see the schematic?

Are you able to turn it on & off with the Arduino?

If you are able to turn it on & off, what happens with PWM? What happens with a PWM value of 254, and a PWM value of 1?

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DVDdoug:
Is that really true? I'm thinking it should work as long as you have a motor driver circuit...

What are you using for a driver? Can we see the schematic?

Are you able to turn it on & off with the Arduino?

If you are able to turn it on & off, what happens with PWM? What happens with a PWM value of 254, and a PWM value of 1?

Here is the original post: Controlling DC Water pump with PWM - General Electronics - Arduino Forum

A few posts down i have posted a hand drawn schematic. I have since replaced the mosfet for a FQP30N06L and added a pull-down resistor at the gate. But it did not work. The pump works fine as long as i supply it with a constant voltage. If i output 254 the pump stops and only makes a little bit of noise. If i output 255 it runs.

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A few posts down i have posted a hand drawn schematic.

Can you give a link to it please as you have split this post.

If i output 254 the pump stops and only makes a little bit of noise. If i output 255 it runs.

What happens with other numbers?

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Can you give a link to it please as you have split this post.

Sure

4032×3024 1.32 MB

NOTE: I have replaced the mosfet for a FQP30N06L and added a pull-down resistor at the gate.

What happens with other numbers?

Same thing. Anything below 255 the motor is just making noise, at 255 it works just as if i had it connected directly to the power supply.

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