Who can help: I need to create a simple alarm (buzzer) that is triggered when the voltage drops.
The alarm should be powerd by a seperate 12V supply.
The circuit should be as simple as possible.
The voltage we are measuring and treiggering the alarm on is on an external ciruit with its own 24V DC power supply. Our alarm circuit should not have an effect on the exisiting circuit. The trigger must operate when the standard voltage drops from 21V (officially this is 24V DC) to below 5V (it seems to drop to about 1.8V and not to 0V, not sure why). I have 8 of these points and the alarm should be able to be triggered on any of these. Once the buzzer goes we should be able to disable to buzzer for 5 minutes by pressing a button.
Is there anybody that can help me with this design? I can manage most of the circuit but the trigger voltage drop from 21V to 1.8V is causing me some issues. I thought of using an Optocoupler or comparator but most designs are based on the Alarm circuit and the external citcuit having the same ground and this is not the case here as both systems will have their own power supply.
The alarm should be powerd by a seperate 12V supply.
The circuit should be as simple as possible.
The voltage we are measuring and treiggering the alarm on is on an external ciruit with its own 24V DC power supply. Our alarm circuit should not have an effect on the exisiting circuit. The trigger must operate when the standard voltage drops from 21V (officially this is 24V DC) to below 5V (it seems to drop to about 1.8V and not to 0V, not sure why). I have 8 of these points and the alarm should be able to be triggered on any of these. Once the buzzer goes we should be able to disable to buzzer for 5 minutes by pressing a button.
Is there anybody that can help me with this design? I can manage most of the circuit but the trigger voltage drop from 21V to 1.8V is causing me some issues. I thought of using an Optocoupler or comparator but most designs are based on the Alarm circuit and the external citcuit having the same ground and this is not the case here as both systems will have their own power supply.