Bill says:
July 13, 2025 at 6:30 pm
For many years the go-to for timebase generation was the unijunction transistor. You can make a nice sawtooth generator relaxation oscillator with just a battery, UJT, three resistors and one capacitor. The linearity of the ramp is quite good.

Here’s an example: https://www.tutorialspoint.com/pulse_circuits/pulse_circuits_ujt_as_relaxation_oscillator.htm