Fluid level detector circuit using 741 op amp

This fluid level detector circuit sensor is based on a simple common 741 op amp IC used as an comparator . When that two fluid level sensor( can be used two pieces of small PCB  or some conductors ) are not placed in liquid the output voltage from the 741 op amp is negative and the T1 is blocked resulting a 0 volts voltage on the R5 resistor  .

If the fluid level sensor are placed in the liquid the output voltage from the 741 operational amplifier is around few hundred mili-volts  and the T1 transistor conducts , resulting an output voltage on the R5 resistor around 4 volts .

With this voltage you can command another device which can do an visual or audio  information about the state of the recipient . For indication you can use an light indicator or a simple alarm circuit .