Originally Posted by Ted Ewert
These are two different devices. The transil apparently acts much like a zener diode, clamping a circuit to a set voltage and shunting any excess voltage.
A sidac becomes a short circuit at it's threshold voltage and only resets when the current ceases. They are primarily designed for use in AC applications. They are relatively low current devices typically handling 1 amp of continuous current with a surge of around 20 A.
I would recommend researching this whole family of devices. Lots of possibilities for the types of circuits we build.
Please , can you explain what do you mean by selected statement ? I've used this device to protect mosfet but I really do not fully understand how it works ? Does it conduct above selected voltage for example when circuit has flyback spike of 300V or it closes when such voltage tries to flow across it ?
Please , it is important for me to fully understand it.I've always thought that it works like a sparkgap passing currents related to voltage above selected level.