Hi!
I wouldn't call it a controller.
Ok, this is a device who can change the behavior of the output voltage by the users wish.
So the user can control through this simple device a dc motor speed or a LED/bulb dimming etc.
Actually it controls something. By the behavior of the input the output is changing.
The intelligent of this device is another story.
There are plenty of high-end and complex controllers and also very basic controllers too but they are all controlling something.
Have an input and make some decision and changes the output.
It's not got any feedback, or even limiting.
A controller don't must have any feedback or any complex intelligent.
That can be done by a cpu also.
A cpu can monitor the rpm, current, pressure, temperature and shut down or make any other
job to control and monitor (in this case the car cab fan dc motor) the whole unit.
And so the cpu (a separated electronic) can be the intelligence of the simple controller like
let's say this device with the ne555.
Let's say, why should I use the cpu power (the pwm pin, code space etc...) for making thinks when there is
a simpler way to do that? Like the ne555 in a pwm signal generator mode with a potmeter on it.
The final user don't know is the potmeter on the cpu or on a separated ic, they even don't care about that.
BD139 is only good for about an amp, you need a much better transistor to handle that.
Yes, that's right.
I will use a MOSFET of course as I also wrote it in my post:
In the future I have to control a larger DC motor through a FET.
10A or so is not a big deal...
https://www.seventransistorlabs.com/Images/555%20Boost.pdf
It's a good info and thank's for it.
The most part from this schematic will be done by the cpu in future in my tool.
I will always stay focused on the questions, simple basic input-output stuff...
Btw.
Thank's for any help, it was very helpful to me and I learned new think's.
My best regards.