[Kevin] doesn’t stock zener diodes anymore. Why? Because for everything he used to use zeners, he now uses TL431 bandgap voltage references. These look like zener diodes but have an extra terminal. That extra terminal allows you to set the threshold to any value you want (within specifications, of course). Have a look at the video below for an introduction to these devices and a practical circuit on a breadboard.

Inside, there’s a voltage reference, an op-amp, and a transistor, so these are tiny 3-terminal ICs. The chip powers itself from the load, so there are no separate power supply pins.

Note that just before the five-minute mark, he had a typo on the part number, but he corrected that in the comments. He goes on to put a demonstration schematic in KiCad. Once it was all worked out, it was breadboard time.

As always, there were a few real-world things to resolve, but the circuit worked as expected. As [Kevin] points out, the faux-zeners are about four for a dollar and even less in quantity. A zener might be a few pennies cheaper, but unless you are making thousands of copies of your circuit, who cares?

We don’t see zeners as often as we used to. As for the TL431, we’ve seen one torn apart for your amusement.