Wow I rejuv old '20's tubes all the time. I just do it the old fashioned way. I'm not all that sure adding a PIC to the process would mean much. There is no such thing as a "safer & gentler" method. You need to bring the cathode to a temperature that is hot enough to bring new material to the surface. This always has the chance of blowing the filament. If done right, this can take from 2 to 20 minutes. I doubt that running it for, exactly, 19.53 minutes is much different than 20 minutes. You run it for a while with the higher voltage then measure the emission. You are the only one that can decide when it is good enough. How does the PIC know that the tube will be bright enough? It might even be over doing it?? Should it be as bright as new?? Should the emission value be the only judge?? Why is it that everyone thinks that a computer controlled or LASER light is better than tried and proven methods. I guess we all just read the labels and except what some marketing fellow wrote. There are some things a computer can do faster than me. It is a little more consistent than me. But it can be consistently bad as well. I guess if the computer blows it up, you can say that it was destined to fail anyway. Anyway, I thought you were talking about one of the old fashioned tester/rejuvenators. They just had a meter needle that was labeled red/yellow/green and a push button labeled Rejuvenate. I guess I'm just out of date. The ones I've seen didn't have a PIC in them. Later Dwight