Fuse failure alarm with 2 LED light

The Fuse failure alarm with 2 led light that LED display when the load is low resistance or short circuit, fuse blow once. LED1,LED2 show fuse state. In circuit use a few parts.

How it works
This circuit will show the performance of the equipment,or Check the fuse in the circuit.The circuit is small and the power supply voltage of all kinds.

It display with LED, 2-color in one. Which is cathode common kind,the anode has two separate terminals. If the circuit is functioning properly LED, it shown in green colour.The display is red, when the fuse in the circuit is damaged.The resistor R1 limits the current to flow through the LED is about 2 mA.This is enough to make the LED light.If it lowers the R1 down, the LED lights up.

Fuse failure alarm with 2 LED light

In the normal operation of the circuit and The fuse is not damaged. The zener diode to prevent the green and red LED lights up simultaneously.Zener diode prevents the LED is green and red lights simultaneously.

The high efficiency LED, when connected in parallel. The red LED uses high-pressure, so that only green LED lights up only. Diodes D3 and D4 will prevent dangerous for the LED. While the half cycle negative voltage of the alternating current voltage.However, if the DC supply voltage.I do not have to use diode protection.

How to build this projects
This projec use a few components so can assemble the circuits in to the universal pcb board in Figure 2 are all components layout of This project.
Which is small PCB.

fuse-failure-alarm-pcb
Figure 2 the components layout.

The components Lists.
LED1,LED2_________________LED as you want.
D1,D3_____________________1N4007__1A 1000V Diode
D2________________________5.1V 0.5W
R1________________________120K 0.5W resistors.

This Post Has 7 Comments

  1. Where can I find the universal pcb that you used iin the led fuse status indicator circuit?

  2. Hi Mark Souhlass,
    Thanks for your feedback.
    You can use bread board pcb. Buy at ebay or Amazon.

  3. There is a fatal flaw in this design.

    As shown, if the load is intact or short circuited when the fuse blows, the full 230Vac will be across both LEDs and the zener diode when the Line terminal is +ve wrt the Neutral line (+ve half cycle) and this will blow both LEDs and possibly the zener.

    The solution is to place an additional 1N4007 at the top of the Green LED – cathode of 1N4007 to anode of Green LED. This will protect both LEDs during both half cycles and the circuit will now operate as intended.

  4. As a postscript:

    I don’t know how much current is required to adequately light the Red and Green LEDs in a bi-color LED but I suspect it is somewhat greater than the 2 mA sourced via the 100K resistor. If using a bi-color LED this resistor can be reduced until both LEDs are sufficiently bright.

    I kept the 100K resistor value and substituted 2mA type Red and Green LEDs. eg. HLMP1700 and HLMP1790 (3mm types) alternatively HLMP4700 and HLMP4790 (5mm types) mounted in suitable panel mount bezels.

  5. Sorry, that should be 120K resistor in both previous posts.

  6. I should read my posts more carefully before sending.

    Please amend the first post to say that the existing D3 should be moved to the top of the Green LED (instead of and addition 1N4007).

  7. this is not working properly
    if circuit is open the red led is not working
    and in circuit is closed the both led are working as dim

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