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Simple Blown Fuse Indicator Circuit with Flashing LED

No more squint eyes at fuse!

This small smart circuit got one blinking LED like little spy for the electronics.

When all seems good an LED will stay bright.

But if fuse go bad maybe too much power or something weird then the LED will start blinking like party light.

That mean something is not right then its time to look and maybe change the fuse.

This circuit uses parts like resistors, one transistor and a LED to watch the fuse and lets one know when problem is coming.

Circuit Working:

Parts List:

ComponentQuantity
Resistors
1k3
100k2
6.6k1
470Ω1
Capacitors
Electrolytic 4.7µF 35V2
Semiconductors
Transistors BC5473
Diodes 1N41482
LED 5mm 20mA1
Fuse1

This circuit keeps a constant watch on DC fuse.

If fuse is okay an LED will stay ON all time.

But if fuse breaks then the LED will start blinking.

Its made for 12V first but if required one can change for other voltage.

For 6V make all resistors half and for 24V make them double.

The circuit uses around 25 mA which mostly go to the LED.

If want to use with battery stuff then it is better to use bright LED that do not require much power.

Also one can change R7 to match that.

Formula:

This circuit use astable multivibrator to show if fuse is blown by using one LED that blink.

How it blink?

The blinking speed (frequency) come from resistors (R1, R2, R3) and capacitors (C1, C2) in the circuit design.

Formula is:

f = 1.44​ (R1 + 2 * R2) *C1

where,

Blinking LED:

When multivibrator change state the LED goes ON and OFF as it blinks.

Blink speed depends on frequency of multivibrator.

Circuit diagram help to find faulty fuse fast and LED blink mean fuse is blown.

If required one can change parts values and test until it work best.

How to Build:

To build a Simple Blown Fuse Indicator Circuit with Flashing LED follow the steps mentioned below:

Get All Parts:

Make Layout:

Start Assembly:

Add Transistor:

Connect LED:

Add Fuse:

Test Circuit:

Change for Other Voltages:

Finish Build:

Put in Box (Optional):

Final Check:

Install:

Conclusion:

Simple Blown Fuse Indicator Circuit with Blinking LED is used in many electronic things where watching fuse is important for safety and fixing.

It help to know fast when fuse go bad and no need to check fuse by hand.

This save time and make fixing easy and quick.

References:

Logic behind this fuse status indicator

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