Zener diodes are a specially made diode that can safely conduct current while reverse biased (RB). Each zener diode has a particular voltage that they are rated to start conducting at while RB. The power supply needs to be at a higher voltage than the zener voltage. A series resistor or something else needs to limit current for the zener diode.

Diagram:

The zener diode can be thought of as kind of a voltage relief valve. Current will pass through it instead of the load as needed to hold the voltage no higher than the zener voltage.

The current through the resistor from the supply must be the combined current needed for the zener diode and the load at that voltage.

It’s better to use the zener diode to set the voltage of a BJT transistor or op amp voltage follower than to try to use the zener diode alone. Future circuits in this series will use those amplifiers with the zener diode.

Video!





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My 74LS00 series IC kit (assuming they haven’t changed it at all)





74HC00 kit that is similar to mine, which isn’t available anymore. List of included IC’s is shown in the images.





4000 series IC kit I have (assuming they don’t changed part numbers)

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