Engineering machinery fuse burnout warning circuit

[0014] Below in conjunction with accompanying drawing embodiment, the present invention is described in further detail:

[0015] figure 2 The shown construction machinery fuse burns warning circuit, including FET 5, current limiting resistor 3, buzzer 9 and warning light 4, current limiting resistor 3, buzzer 9 and warning light 4 are serially connected to FET 5 in sequence. Between the drain D and the ground wire, the two ends of the warning light 4 are connected in parallel with a shunt resistor 8; the field effect transistor 5 is a PMOS field effect transistor; the warning light 4 is an LED light-emitting diode; It is connected with the power supply and the power terminal a of the fuse 1, the load terminal b of the fuse 1 is connected to the gate g of the FET 5 through the input resistor 6, and the load terminal b of the fuse 1 is connected to the ground wire through the pull-down resistor 7. The load terminal b of fuse 1 is inserted into one end of load 2, and the other end of load 2 is grounded; the resistance value of input resistor 6 is equal to 1K ohm; the resistance value of current limiting resistor 3 is equal to 100 ohm; pull-down The resistance value of the resistor 7 is equal to 47K ohms; the resistance value of the load 2 is much smaller than the resistance value of the pull-down resistor 7. In the embodiment of the present invention, the resistance value of the load 2 is less than 1K ohms. For example, the resistance value of the load 2 can be several tens of ohms. or several hundred ohms.

[0016] When the fuse is working normally, the voltage difference between the source S and the gate g is 0V, so the FET is in the off state and the warning light does not work; when the fuse is working normally, the resistance value of the pull-down resistor 7 is much larger than that of the load 2 Therefore, the current passing through the pull-down resistor 7 is very small, and the operation of the load 2 is basically not affected by the pull-down resistor 7; The voltage is equal to VCC, the absolute value of the gate-source voltage | Ugs | > the turn-on voltage of the FET | Ugs(th) |, so that the FET is turned on and the warning light is on, which means that the fuse has been burned, and the staff is reminded to repair it as soon as possible; The warning light and the load of the present invention do not affect each other, even if the load is disconnected at the same time, the alarm of the warning light will not be affected, and the reliability of the alarm is high; at the same time, after the fuse is blown, the fuse load end has been completely disconnected from the VCC because of the fuse disconnection. When the maintenance personnel pull away from the load and measure the load terminal of the fuse, the voltage value measured is zero, which ensures that the maintenance personnel can find out the source of the fault as soon as possible.