Need to sense and alarm 4vdc

I have a RV and just installed a monitor to show the level in the waste and fresh water tanks. The monitor has a 0-5vdc output with 0 volts empty and 5 volts full. I would like a way to sense the voltage and activate a buzzer or alarm at 4 volts.

Thanks, Dan

Fairgrove said:

I have a RV and just installed a monitor to show the level in the waste and fresh water tanks. The monitor has a 0-5vdc output with 0 volts empty and 5 volts full. I would like a way to sense the voltage and activate a buzzer or alarm at 4 volts.

Thanks, Dan

Click to expand...

hi Dan,
A simple way would be use a LM393 compartor ic.
The threshold switching level can be set by using a variable resistor.

How are you with electronic circuitry.? how much help do you need.

I am rookie that knows just enough to get in trouble

I need help with a schematic. I have done some very fundamental stuff but I don't think this is all that complicated.

Fairgrove said:

I need help with a schematic. I have done some very fundamental stuff but I don't think this is all that complicated.

Click to expand...

hi Dan,
I'll post a diagram this weekend... unless some other member has one already drawn.

hi Dan,

Attached drawing for the LM393 version of the voltage level detector.
I have used the 2nd half of the LM393 as a detector for less than +1V.

Have a look and let me know if its what you looking for.

NOTE: the bleeper is a tone bleep driven from a Vdc fro 5V thru 12V, they are not very expensive.

The relay output option could be used to switch OFF a device when the tank is nearly full. A relay could be added to the 2nd part to control the tank filler.

In order to check out the circuit, I have built it on a project board, it works OK.

Hi Fairgrove,

Here's another one.

on1aag.

Thanks Eric

I won't be where I can buy the componets until the end of next week. I am out in the desert of Southern California right now. I am headed to Wichita Falls Texas next week. The link below will show the different monitors. The one I have is the 709-RP because it has the outputs.

Thanks, Dan

https://www.rvgauge.com/products/model_709RP.shtml