Selecting MOSFET Configuration

[LukeKnepp]

Hello Everyone...

I am trying to make a Low Voltage Buzzer Warning that beeps on and off, without a microcontroller....
I have a latching detection circuit here that puts out about a 6V signal until the battery is dead, then it drops off and latches off until it is reset....

This is the signal that I get....

Now, what I want to know is what kind of MOSFET do I need, and what kind of driver circuit do I need to make this switch ON a buzzer whenever this signal shuts OFF.....

Thank you for your help!!!

 

[rjenkinsgb]

You could switch the buzzer using a FET plus a high value pull-up resistor, eg. 1M or higher, from the gate to power positive.

Then add another FET between 0V and gate of the buzzer control, with its gate to your control voltage.
The buzzer would be held off with its gate shorted to 0V, until the low voltage circuit tripped.

 

[LukeKnepp]

P-Channel or N-Channel MOSFETs?

 

[rjenkinsgb]

N-Channel, both with source to 0V / gnd