How can I build a simple pulse generator to demonstrate transmission lines

Decades ago we used a much simpler method. A few 50 or 75 ohm non-inductive resistors and a tunnel diode.

Feed any (slow) pulse generator into the diode and make it switch. Tunnel diodes can have sub-nanosecond switching times.

We also used this technique to check/measure the rise times of our oscilloscopes.

Nice write up and sneaky introduction to time-domain reflectrometry but I'd like to point out the classic answer to this question is the famous Jim Williams pulse generator: https://github.com/podonoghue/Jim_Williams_Pulse_Generator?t...