This basic circuit published at https://www.facebook.com/share/p/1Gi4UZHpVh/ claims to be able to serve as an instantaneous way for you to detect whether it is in fact due to a blown fuse or not. It is a small circuit that tries to make your job as an electronic technician easier.

When the fuse is in working order the LED remains “off.” When the fuse has blown, however the LED lights up to provide you with an obvious notification of the blown fuse condition. Therefore, you do not need to guess or waste time continually re-checking the same device as this simple idea can save so much troubleshooting time and effort when working with power supplies or batteries.

#innovation #learning #electronicproject #simplecircuit

Could this build in a simpler way?
Why not simplify the circuit by wiring the LED directly across the fuse ( with a current limiting resistor )

Source: https://theorycircuit.com/electronics-projects/blown-fuse-indicator/

The downside of his idea:
1. When fuse blows, there is no reliable full isolation of load because of the current through LED
2. If load is removed, LED does not indicate blown fuse

Another way it so place a power indicator across the supply after the fuse. It works by showing if power gets through the fuse or not. The downside is that the indicator LED will consume power all the time when power is on.

Links to other ideas:
https://dmohankumar.wordpress.com/2015/10/21/blown-fuse-indicators-simple-design-10/
https://www.eevblog.com/forum/projects/blown-fuse-indicator-design-validation-automotive/
https://electronicsarea.com/blown-fuse-indicator-circuit-using-one-transistor/
https://theorycircuit.com/electronics-projects/blown-fuse-indicator/
https://www.edn.com/simple-blown-fuse-indicator-sounds-an-alarm/

Miten hyödyntää Moderni C++ -ohjelmointikieltä tehokkaasti ja joustavasti?
https://www.tieturi.fi/webinaari-miten-hyodyntaa-moderni-c-ohjelmointikielta-tehokkaasti-ja-joustavasti/

Modern C++ Design Patterns Full Course

C++ Design Patterns – The Most Common Misconceptions (2 of N) – Klaus Iglberger – CppCon 2024

Hands-On Design Patterns with C++ by Fedor Pikus

Design Patterns in C++

Modern C++ Design Patterns Tutorial

Design Pattern Catalogue

Singleton Pattern | C++ Design Patterns

Observer
Also known as: Event-Subscriber, Listener
Observer is a behavioral design pattern that lets you define a subscription mechanism to notify multiple objects about any events that happen to the object they’re observing.
https://refactoring.guru/design-patterns/observer

Strategy
Strategy is a behavioral design pattern that lets you define a family of algorithms, put each of them into a separate class, and make their objects interchangeable.
https://refactoring.guru/design-patterns/strategy

How to Create Custom Memory Allocator in C++?

Template Metaprogramming in C++

From C++ Templates to C++ Concepts – Metaprogramming: an Amazing Journey – Alex Dathskovsky

Embedded C++ : to use STL or not?

Standard Template Library (STL) in C++
https://www.geeksforgeeks.org/cpp/the-c-standard-template-library-stl/
https://en.wikipedia.org/wiki/Standard_Template_Library

In embedded systems, how much memory C++ STL uses depends heavily on:
The container type
The number of elements
The implementation (libstdc++, libc++, etc.)
Whether dynamic allocation is used
Compiler optimization settings
There is no fixed memory cost, but I’ll break it down clearly.
Heap Usage (Critical for Embedded)
Most STL containers use dynamic memory (new).

Problems in embedded:
Heap fragmentation
Unpredictable allocation time
Memory exhaustion
No control over allocator unless customized

STL within embedded system with very limited memory
https://stackoverflow.com/questions/9612588/stl-within-embedded-system-with-very-limited-memory

Understanding Memory Management, Part 2: C++ and RAII
https://educatedguesswork.org/posts/memory-management-2/

Copper wire vs bananas vs mud – An interconnect test
https://www.diyaudio.com/community/threads/copper-wire-vs-bananas-vs-mud-an-interconnect-test.420367/

Audiophiles Can’t Differentiate Audio Signals Sent Through Copper, Banana, and Mud in Blind Test
https://www.headphonesty.com/2026/01/audiophiles-fail-copper-banana-mud-blind-test/
https://www.reddit.com/r/audiophile/comments/1qrk2hu/audiophiles_cant_differentiate_audio_signals_sent/

Are audiophile cables a scam? Copper VS banana VS ???

View also short Video

Man Uses Baby Carrot as RCA Adapter and It Actually Works Better Than It Should
https://www.headphonesty.com/2024/12/man-uses-baby-carrot-rca-adapter/

Audiophile Carrots are a thing now.. Listen to it for yourself!

I post links to security vulnerability news to comments of this article.

You are also free to post related links to comments.

The found Ukranian drone is type Antonov An-196 Liutyi.

Here is current GPS interference map from https://gpsjam.org/ with city of Kouvola added to it:

Sources:
https://www.euronews.com/2026/03/29/two-unidentified-drones-crash-in-southeastern-finland-in-suspected-territorial-violation
https://yle.fi/a/74-20217941
https://yle.fi/a/74-20217933
https://gpsjam.org/
https://yle.fi/a/74-20217966

This is a bad and dangerous design

This is a dangerous design. There is potentially lethal voltage on those probe pins. ⚡️☠️
I strongly discourage to build this.

Design problems
- no isolation from mains – test probes and circuit being tested dangerous to touch
- pointless filter coil in output
- open circuit voltage can be over 300V
- output capacitor in circuit directly on probes – high current surge when you connect probe can potentially damage LED being tested

According to the latest edition of the World Happiness Report, the three happiest countries in the world are Finland, Iceland and Denmark.

Finland was named the happiest country in the world for a record 9th time in a row,

There is seen a sharp drop in youth happiness in very many countries: A key factor in the sharp drop in youth happiness, researchers said, is the number of hours young people spend consuming social media or gaming. While experts say it’s important to limit time spent with the Internet overall, some ways of spending time online are healthier than others. A key question is “if they are really social media or anti-social media.”
“The digital age is reshaping the social and emotional foundations of wellbeing in Europe”

Source:
https://www.cnn.com/2026/03/18/travel/worlds-happiest-countries-2026-wellness

It is a working concept but bad viral implementation: That 100 ohm resistor will heat up and consume the battery quite quickly. The 100 ohms resistor is so low value that it can potentially damage the transistor because maximum allowed transistor base current is exceeded when alarm is activated (detection wire is cut).

Here is a video of one alarm build with more sensible resistor value:

Here is another design from
https://www.facebook.com/groups/electricaltechnicaltips/posts/1299510351762337/

This is a simple **Wire Cut Alarm Circuit** designed to detect when a wire is cut. It uses a **BC547 NPN transistor**, an **LED**, resistors, and a **3V battery**. The red wire connected through a 10kΩ resistor to the transistor’s base acts as a trigger. As long as the wire remains intact, the transistor stays off and the LED remains off. If the wire is **cut**, the base of the transistor no longer receives voltage, causing the transistor to **turn on**, which in turn **activates the LED**, serving as an alarm. This type of circuit can be used in basic security systems to alert when a connection has been tampered with.

This is a classic transistor-based “normally closed” (NC) alarm circuit. It uses a BC547 NPN transistor as an electronic switch to monitor the state of a physical wire.

1. Key Components

BC547 Transistor: The “brain” of the circuit. It acts like a gate that only allows power to flow through the LED if it receives a small voltage at its Base (Pin 2).

100kΩ Resistor: Acts as a “pull-up” resistor, trying to turn the transistor ON.

10kΩ Resistor & Wire: Act as a “pull-down” path, keeping the transistor OFF while the wire is intact.

2. How it Works (The Logic)
State A: The Wire is Intact (Alarm Silent)

When the red wire is connected, it creates a path to the negative terminal (ground).

The two resistors (100kΩ and 10kΩ) form a voltage divider.

Because the 10kΩ resistor is much “weaker” (lower resistance) than the 100kΩ resistor, it pulls the voltage at the Base (Pin 2) down very close to 0V.

An NPN transistor needs about 0.7V at its base to turn on. Since the voltage here is roughly 0.27V, the transistor stays OFF, and the LED remains dark.

State B: The Wire is Cut (Alarm Active)

When you cut the wire, the path to the negative terminal is broken.

The 10kΩ resistor is now “disconnected” from the ground.

The 100kΩ resistor is now free to “pull” the Base voltage up toward the full 3V of the battery.

The transistor turns ON (enters saturation), allowing current to flow from the Collector (Pin 1) to the Emitter (Pin 3).

This completes the circuit for the LED, and it lights up.

LED Protection: The diagram doesn’t show a current-limiting resistor for the LED. Depending on the transistor properties (current amplification factor that vary in 110 – 800 for BC547 transistor) there might or might not be current limiting for LED. While a 3V battery might not immediately blow a standard red LED (which usually handles ≈2V), it’s best practice to put a small resistor (like 100Ω) in series with the LED to prevent it from burning out over time.

Sensitivity: Using a 100kΩ resistor means the “trigger” current is very low, making the circuit very power-efficient while in “monitoring” mode.

Related links:

Wire Break Alarm Circuit With IRFZ44N MOSFET
https://www.instructables.com/Wire-Break-Alarm-Circuit-With-IRFZ44N-MOSFET/

How can I make an alarm circuit which senses both cutting and shorting the wire?
https://electronics.stackexchange.com/questions/699628/how-can-i-make-an-alarm-circuit-which-senses-both-cutting-and-shorting-the-wire