In the figure we have the way to implement a power zener diode. The voltage depends on the zener, and the maximum current of the transistor.
This interesting circuit, which can be used as an alarm, was found in a 1997 documentation. It...
We found this circuit in the National Semiconductor FET manual. The components are calculated...
The presented circuit is suggested by Texas Instruments (www.ti.com) in its Application Report...