Blown Fuse indicator circuit with LED Display

This is a Blown Fuse indicator circuit by LED Display. A Fuse be the equipment protects that use often most. Because of cheapness can use protect electronics expensive circuit. Generally when fuse torn us can know immediately. but in sometimes Fuse torn already we don’t know. such as in electricity automobile system brake system , the system delays the electric current very much, etc. Fuse torn get into trouble at we must know for immediately the safety.

Blown Fuse indicator circuit with LED Display

Figure 1 The Blown Fuse indicator LED Display circuit.

So I would suggest this circuit is simple. It can show with LED that immediately when Fuse blown. See the illustration as Figure 1
In normally or Fuse is good, Current flow through it to D1-diode 1N4148 as forward bias, so cause Q1-PNP transistor do not conduct current, It not work so LED go out.

But Fuse blown or Damaged by high currents from overload, cause open circuit. So there the base current to Q1 it so bias or has higher current flow through R1-resistors, collector, emitter of Q1 and LED1 glow immediately.

by equipment value that show that note for Voltage Source 12V , but if friends want to apply to the level Volt the other.

As a result change value R1 and R2 get by can calculate from R1 = (Vin – 2) x 50 and R2 = (Vin – 2) x 10000/2. Think the work of the circuit has a little, It may help to give friends comfortably up.

How to builds

This project is not used many components so can assemble on the universal PCB Figure 2 and Figure 3 The wiring and placing components must be carefully for is the polarity of Diodes, LED , transistor BC558 correctly.

Figure 2 Prototype Blown Fuse indicator LED Display.

Figure 3 Copper of the PCB of Blown Fuse indicator LED Display.

And see below…

I check Fuse OK, then put it in circuit next power supply to circuit, and lastly Short circuit! Ohh LED display immediately. This circuit works!

Fuse status indicators for 12 volts power supply

This circuit is a Fuse status indicators for power supply 12V. If a fuse is normally, the LED is going to lights all the time. But when it lacks, the LED will be blinking. The value of this equipment in the circuit is suitable for a 12 volt power supply.

However able to change the power supply 6 volt or 24 volt, By reducing the value of the resistor to half or increasing.

The display section consists of a stable multivibrators (Q1-BC547, Q2-BC547). And the driver LED section (Q3), All circuits except for the R5 connect before the fuse.

Fuse status indicators for 12 volts power supply

The output of the multivibrators is going to work all times there are power supply, by passed through the diode D2 to the input of the driver LED section (Q3‘s PinB) If the fuse is intact , the base current of Q3 has still always, by passed through R5 and D1,the color LED shown constantly. But when fuse in blown condition,the driver current Q3 is going to get from only multivibrators, so the led is flashing.
The current rate of Power consumption about 30 mA, by almost all were used by the LED. If you are used this circuit with some circuit that uses a high quality LED and changed R6 values to suitably with the lower current of the LED.

LED Blown AC Fuse Indicator Circuit Diagram

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-voltage 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 project uses a few components so can assemble the circuits into the universal PCB board.

Read Related circuits post.

+ Fuse status indicators for 12 volts power supply

+ Use SCR help give fuse torn fast

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nana kwadwo

i wont to know the means of operation of Blown Fuse indicator LED Display


Dear can we use this circuit for AC indicator…

MR OHM 1970

Dear sanjeev It can be done but it is more complex and dangerous since you are dealing with 120 or 220 VAC!!!

MR OHM 1970

Once Again A Fun Easy To Build Circuit…THANKS GUYS!!!!!

MR OHM 1970

When the fuse is good There is +11.3 volts on the Base of the Transistor(PNP) So The Transistor Is Cutoff, When The Fuse Blows The Voltage is 0 Volts or More Negative than 11.3 volts, and Now The Transistor is switched ON , Hence The LED now Lights Up…Simple But cute Little circuit!!!!

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