Three Speed Fan Control

Thread Starter


Joined Jul 22, 2022
This is a 3.6V 3 speed fan control. The LEDs cycle with the power progression. The chip KW518 is not an accurate label and the chip is custom from what I can tell. The chip is powered when battery is plugged in and has 4 button presses to cycle through. Low med high off. Pin 2 gives battery voltage for low med and high and off for off. Pin 3 and 4 go to ground. Neither on low. Pin 4 for med and pin 3 for high. I made a chart with each pin voltage reading at each button press.

I am trying to understand how this chip works or at least how pins 3 and 4 get switched to ground/(-) internal to the chip.

I am crash coursing into integrated circuits with this and would like to be able to reproduce a circuit with similar function. I don’t need the LEDs but like the 3 speed with single pushbutton control. I intend to use the circuit with a different fan type so I need to change the output voltages. I think I am correct in saying resistors 2, 5, and 6 will change my outputs.

If you know of a chip that’s easily available with similar function that would be great and I could go through the data sheet on it.

I have a background in electronics but Im more geared towards PLC’s and Im finding thinking in terms of integrated circuits fairly difficult so far.