Looking for help with a scan/ sonar effect

Hi everyone so i have created an effect similar to this as a material UE4 Questions & Answers: Dynamic Scan Post Process FX - YouTube and I’m really happy with how it has turned out, the only issue is that i don’t want it to be constantly firing, i want it to only happen once on a key press within ue4, I’m not really sure how to go about this though

I too am trying to do this and I was able to make it go invisible then visible again but not off/on, if that makes sense. So I have the key press working, I just need to either reset the material when I press F (my Key press) or after 3 or so seconds switch out the material for a blank material and then apply the Echo Location Material (Sonar) when I press F again. Been having troubles with this for a while. This is what I have so far…