I know very little about circuits and electrical components, so please be kind.
Attached is a picture of a simple circuit. "A" is a 4,5V AAA alkaline pack, "B" is a latching pushbutton switch and "C" is a nicrome wire.
In the simplest and cheapest way possible, this circuit needs to alert the user if the battery pack goes below 3V. The indication signal needs to be a "beep", just like a smoke detector. (I can't have a LED signal).
After some googling, I found that a 3V "low signal relay" incorporating an alarm/buzzer could be one option. I prefer to use wires, and not a PCB in my circuit.
My questions follow below:
1. Is a low signal relay this the cheapest and simplest way, or are there others?
2. Do these relays come with a beep sound?
3. When in standby-mode, this relay should not draw power from the alkaline pack, therefore it needs to be powered from an external (coin cell?) battery.
Is there such a product that I can buy off-shelf and where in my curcuit do I fit it?
All help highly appreciated.