A Simple, Valve Curve Plotter

[Alan Douglas]

I've always had regulated power supplies around, for HT, and I've always used similar supplies for grid bias. So the tracer itself contains only sockets, switching, and perhaps meters. I've built a couple. I used X-Y plotters for the permanent record; they're also faster than reading meters by eye, so you can run tubes in overload for very short times and get points on the curve you couldn't normally. These days you can't give away X-Y plotters and I have several. I also played around with CRT tracers. But that was all years ago when I was writing my book on test gear.