Transistor Circuit that is normally closed?

[icedeocampo]

I wondering if we can implement a transistor switch... that is remains in an "on" state for voltages below 14v and... and it will be in an "off" state when a the voltage is greater than or equal to 14v.

The circuit should be able to switch around 5Amps.

Can you guide me as to what path to take... thanks !

 

[Papabravo]

A TIP34C PNP power switch will exhibit this behavior with a Vcc of 14.7 volts. Will this work for you? You'll need quite a bit of base current for this though.

 

[icedeocampo]

Hmm... would a 3A be enough?

Here's the whole scenario... I have motorbike... with a stator that produces anywhere from 22v to 60v, I rectified that AC (half wave)

Another topic I've posted is how to make a shunt regulator for it, so im exploring different posibilities.

and I need to regulate it to feed it to a battery... My idea is basically... the transistor should work like a very fast switch... fast enough so it'll feed something to the battery, but it should not exceed a certain voltage.

im really sorry because I'm really new in electronics, would you be able to help me comeup with a schematic diagram, thanks

If 14.7 would be the cutoff, I'll probably use a series of diodes to drop the voltage... would that be possible?