Variable resistor of boost module

Hello!
Korea is lunch time soon.
I am curious about the boost module.
For example, it is a product like the attached image.

When using the product for the first time, the variable resistor must be turned several times.
After that, there is a reaction by turning a little.
I am so curious about this.
Why does it have to react several times at first?

I can only interpret English, so I write it with Google Translator.
Sorry about this.

Perhaps it has to be turned enough to work with the incoming voltage to start.
For example, if the incoming is 3.3V and you trying to see 5V, then the resistor must be adjusted so that the output exceeds the input before yous start seeing better results.

Do you have a part number for the board, and where it came from?

The picture above is an example.

I'm actually curious about the descent module.
This is the link product below.
(PWM直流电机调速器5V-35V调速开关 5A开关功能 LED调光器-淘宝网)

There is no picture, it is on your private Google account.

From the taobao item:


It is not immediately obvious, but this may be a multi-turn potentiometer. There is a certain minimum PWM value required before the motor overcomes its friction and starts up.

This is I think a simple PWM motor controller, not a "boost module".

I agree - static friction due to brushes is large in brushed DC motors, and motor torque is set by the current.
So the current has to rise above this limit before anything happens.

Once moving and warming up motor friction will usually reduce a bit, so there is hysteresis in the setting.

PWM control is not linear speed control, nor is it linear torque control.

Hello!

Ah!!! I'm really sorry.
I wrote another link.

So, this device then:

Well, this is definitely a multi-turn potentiometer - generally a "ten-turn" one.

This means you must turn the screw ten complete revolutions in order to move it from one end of its range to the other. The position you want will be somewhere in this range, but will not likely be near either end, so you have to turn it a bit before it is near the right position.

Ten turn or multi-turn "pots" allow you to make very small and detailed adjustments.

Thank you for the reply! : )