Simple Blown Fuse Indicator Circuit with Flashing LED

Stop squinting at your fuses!

This clever circuit with a flashing LED is like a tiny snitch for your electronics.

Normally, the LED stays bright, letting you know everything is humming along.

But if a fuse blows because of a power surge or something wonky the LED starts blinking like a disco ball.

That is your sign to check things out and replace the fuse.

This circuit uses resistors, a transistor and an LED to keep an eye on your fuses and give you a clear warning when something goes wrong.

Circuit Working:

Parts List:

This circuit serves as a monitor for a DC fuse.

When the fuse remains intact its LED remains continuously lit.

However, if the fuse is broken the LED blinks.

Originally designed for 12V the fuse monitor circuit can be adjusted for other voltages.

To adapt it for 6V halve all resistance values, for 24V double them.

The circuit draws approximately 25 mA with the LED accounting for most of this current.

If incorporating the circuit into battery operated modules, it is advisable to opt for a high efficiency LED and adjust the value of R7 accordingly.

Formula:

An astable multivibrator setup is used to construct a transistor based blown fuse indication circuit with a flashing LED, which is explained with the below mentioned formula.

Establishing the Oscillation Frequency:

A stable multivibrators oscillation frequency (f) is set by the resistors (R1, R2, R3) and capacitors (C1, C2) in the circuit.

f = 1.44​ (R1 + 2 * R2) *C1

where,

• R1 and R2 are resistors connected to the base of the transistors.
• C1 is the capacitor that is linked to one transistors base and collector.

Flashing Light Emblem:

When the astable multivibrator shifts states, the LED flashes on and off.

The multivibrator circuits oscillation frequency controls the flashing rate.

The circuit diagram makes it simple to identify and troubleshoot fuse failures in electrical or electronic systems by utilizing a blinking LED to visually indicate a blown fuse.

For your particular application, adjust component values and test the circuit to get the best possible performance.

How to Build:

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

Components:

• Gather the necessary components as mentioned the diagram above..

Layout Design:

• Plan the layout of the components on a prototyping board or PCB according to the circuit diagram.
• Ensure proper spacing and connection paths.

Assembly:

• Start by soldering the resistors and other passive components onto the board following the circuit diagram.
• Pay close attention to resistor values and their placement.

Transistor Placement:

• Solder the transistor onto the board ensuring correct orientation as per the circuit diagram.

LED Connection:

• Connect the LED to the circuit, ensuring the proper polarity anode to positive, cathode to negative.
• Consider using a high efficiency LED if operating on battery power.

Fuse Connection:

• Connect the fuse holder to the circuit.
• Ensure it is properly wired inline with the circuit and that the fuse rating matches your application requirements.

Testing:

• Before sealing the circuit, test it to ensure proper functionality.
• Apply power and verify that the LED behaves as expected: continuously lit when the fuse is intact and blinking if the fuse is broken.

Adjustment for Different Voltages:

• If using a different voltage than the original design e.g. 6V or 24V adjust resistor values accordingly as per the provided instructions halve for 6V double for 24V.

Finalization:

• Once testing is successful and adjustments are made for different voltages finalize the circuit assembly.
• Ensure all connections are secure and insulated to prevent short circuits.

Mounting:

• If necessary, mount the circuit in an appropriate enclosure or housing to protect it from environmental factors and ensure safe operation.

Verification:

• Before deploying the circuit in your application verify its functionality once again to ensure it operates as intended.

Installation:

• Install the circuit in your desired application ensuring proper wiring and connections to the power supply and the device being protected by the fuse monitor.

Conclusion:

Blown fuse indicator circuits with flashing LEDs are commonly used in various electronic devices and systems where monitoring the status of fuses is essential for safety and maintenance purposes.

They provide a quick and easy way to identify fuse failures without the need for manual inspection, thereby facilitating prompt troubleshooting and maintenance actions.

References:

Logic behind this fuse status indicator