Automotive electrical network voltage regulation monitoring circuit

Abstract

To provide a visible output indication, for example by an indicator light on a controller supervisory panel of the vehicle, of proper functioning of the voltage regulator power transistor, monitoring circuits are provided which sense the electrical condition of current flow through or the voltage condition of the field winding or output bus respectively by including a light emitting diode (LED) in an indicator circuit, for example by connecting it in series to the coupling resistor. In one form, a Zener diode Z (FIG. 1) is connected across the output bus with the LED in series, so that the LED will light if the output bus reaches a voltage which might damage the battery, for example due to short circuit or alloying-through of the output transistor T of the voltage regulator; in another form, an LED which preferably is green, LDg (FIG. 2), is connected across the output transistor, the green LED lighting if the output transistor functions properly, but extinguishing if the output transistor alloys-through; the LED with the Zener diode and the green LED can be provided together to form alternate outputs--green indicating proper operation and red already danger; in another form, an LED, preferably also green (FIG. 3) is connected across the field winding so that, if the output transistor T' should burn through, extinction of the green diode will indicate that the field no longer receives energization. Of course, the usually provided charge control lamp will then also light since the alternator will no longer furnish output, so that the combination of the green LED across the field with the charge control lamp again provides an alternate output indication, the extinction of the particular green LED pinpointing the trouble which caused the charge control lamp to light.