I am trying to simulate open/short conditions for testing an optoisolator circuit I'm building.
Essentially, I need to simulate SHORT and OPEN in order to verify that what I'm designing will output the desired voltage difference instead of either infinite or none.
Here is an image of the part I'm playing with. It uses a PC817 as the photocoupler, and I'm building a box with two of them where one functions just as an isolator, and the other functions to translate a sensor from purely outputting OPEN or SHORT conditions, to different voltages so our devices can read it. In short, I need to know how to simulate OPEN and SHORT conditions to verify that the circuit I make will do what I need it to.
Best Answer
There are a few ways, one is using a relay or switch to change a load (A resistor with 1e9Ω is a good approximation for an Open condtion and something small like 1mΩ is good for simulating a short).
Another way to do this is to use a variable resistor (a regular resistor with the value set to R=V(node).