Trouble Using Arduino as a Timed SPDT switch

Projects General Guidance
1

First time trying to use an Arduino and could use some help. I have a controller with a manual print button that I'm trying to automate on a regular time interval using my Nano.

The way it is wired now, there's a momentary switch with two leads that when not pressed has +5V across them. When pressed, the potential drops to 0V and it prints. It's a low current circuit so I figured I wouldn't need a relay to do the switching, as I know the pins on the Nano can handle up to 40mA.

I tried to repurpose the blink library example and am able to get the output on Pin 13 to loop +5V to 0V back to board ground, but when wired in-line to the circuit doesn't work as expected. Any help would be appreciated.

2

Did you connect the grounds of the Arduino and the printer?

The proper way to make the connection and not to worry about the grounds is to use an "opto-isolator". Google that. It is an LED and a transistor. Your Ardiuno turns on the LED and the transistor is turned on by the LED light, which switches the printer signal to ground, just like the mechanical switch does.

Paul