When in an older vehicle the temperature- or the fuel gauge suddenly, begins to go haywire, one can be fairly certain of a defect in the voltage regulator. What now has to be done, is assembly work, because one has to
remove the instruments to replace the component which is mostly found at the rear. In the journeymans tests the voltage regulating diodes are also often discussed.
It is named after Clarence Melvin Zener, who tested whether certain diodes, operated in the reverse direction, and above a certain voltage, will let (low resistance) current through. Basically Their reverse effect is
then lifted. How can this behaviour then be used to stabilise the voltage? In this case one must operate the Zener diode in the reverse direction together with a serially switched resistance. One reverses, as it were, the
behaviour of the diode. The voltage for the consumer to be protected, is taken from both sides of the Zener diode. If the desired maximum voltage is exceeded, the consumer is bridged by the Zener diode, and thus
In voltage regulators with three connections, the resistance is already built in. It is delivered for the respective maximum voltage and for a, mostly low current. The connections are given from the two different voltages
and the common negative terminal. 04/07