I am currently on my own project building a blower that can be controlled using a switch with 2-3 speed mode powered by 12V Li-Ion Battery with hope this can support local health workers. However, I kind of hitting a wall since I less familiar with electricals, and currently did not have anyone close to consulting these particular matters in college due to the pandemic.

The question that I would ask is whether this is a proper schematic or not?

Blower with 3 speed schematics

I also add some feature like a low-bat indicator alarm, battery indicator module, and make sure the battery disconnects while charging. However after I run several tests to this schematic, I find that 1) the blower sometimes stutters, 2) Whenever I change one of the trimpot value it affects the other speed mode (Like I want this "Fast" mode a Lil bit faster, but when switched to "slow" mode the speed changes despite the "slow" trimpot value left untouched). 3) Run test on the alarm, it was supposed to go off on low voltage. But what I got is it go off at high-volt, not when low-volt. 4) I happen to add some filters and found the pressure drop was too great and I was intended to add more speed to the blower. But I cannot figure it out which to alter. Changing the trimpot only adds more power a bit or should I change the regulator to higher output?

The blower I used is WM7040. However, it has its own speed controller using a potentiometer. After looking at its datasheet (Here's the datasheet), I did some redesign substitutes the rotary pot to 102/103 trimpot or you might see in schematic listed under R5, R6, and R7. X2-x; and X4-x connects to the blower controller. X1-x connects to the battery, and X3-x connects to the bat-indicator module.

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The following question appears after the last test:

  1. Did I need to add a higher voltage to the controller? I did use a 9V regulator on the blower.
  2. Why problem number 2 happens? Thought it was Kirchoff laws apply here, or it just comes from the controller schematic? if it did comes from the controller, did the blower powered not directly powered from the 5v pin to the potentiometer I presume?

Sorry if I explain it too vague. You did not have to answer directly right away. I just kind of bamboozled or lost in thought, a review on my first schematics, and a few hints of improvements are welcomed.

Thank you in Advance



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