A while back I was going on a theory on a quick and simple Curve Tracer. Well I was dead wrong on a lot of it.
Lets talk about the Octopus circuit. It’s more of a passive component tester. A lot of scopes have this option built in. A real Curve Tracer is more geared towards Transistors, Diodes and Thryristors.
The TV CRT is not a good candidate. The CRT has to be a Electrostatic. Vintage TVs from the late 40s and up to the late 50s used Electrostatic CRTs. However you can find all over eBay Oscilloscope CRTs from ten bucks and upwards to eighty bucks.
To create a more of a real Curve Tracer I would check this out. The circuit uses a stair-step generator from a 555 timer and some Op Amps. However it looks like it can only do NPN transistors. Not to mention a scope that can do a X-Y function.