Need some help mimicking a switch

Hey everyone,

I have an application where I need to mimic a switch based on interoperation from my arduino.

To clarify, I don’t necessarily need to use my arduino, just not sure how else to do the interpreting.

Here is my situation, I have a CNC parallel port breakout board. It has 12 pins.

Pin 11 and 12 are power, 11 is positive, 12 is supply ground.

Pin 1 is an input pin, and the way it is triggered is by connecting pin 1 to pin 12.

I am trying to measure the RPM of my lathe spindle and trigger my Pin 1 every one full revolution.

I created a IR emitter/detecter that can read a disk that I put on my spindle, with one white line on it, and the rest black. That sends out an analog signal.

I am capturing the analog signal with my arduino, but I cannot figure out a way to sink pin 1 and 12 when the white line happens.

Any ideas for me? I can use my arduino, but I certainly don’t have to.

Everytime the white line comes around you get a voltage change, either high or low, right? Might be as simple as taking that output into the base/gate of a transistor connecting 1 and 12. Might need a pull up or pull down resistor to keep things from floating. If the white line triggers a high pulse, the transistor should conduct between 1 and 12 for each pulse.

This could definitely work, in fact, I think I can bypass my arduino altogether with this.

I could probably send my analog signal to the base of an NPN like a 2N2222 through a small resistor, and have my collector connected to my 12 pin and my emitter connected to my 1 pin.

Thank you, I was trying to overcomplicate this!