Simple Short Circuit Protection Circuit with Auto Reset | DIY Electronics Project

Описание: Looking for a 5-12V DC short circuit protection circuit with auto reset? In this video, I will explain a simple and reliable short circuit protector built using two transistors with dual LED indication.

This circuit protects your power supply from damage during overload or short circuit conditions and automatically restores power once the fault is removed — no fuse replacement required!

🔧 Main Components Used:
BD139 NPN Transistor
TIP42C PNP Power Transistor
Resistors (1KΩ, 10KΩ, 220Ω)
Red & Green LED indicators
5–12V DC Supply

⚡ How It Works: Under normal conditions, the TIP42C allows current to flow to the output and the Green LED indicates normal operation.
When a short circuit occurs, BD139 detects the voltage drop and turns off TIP42C, cutting the output supply immediately. The Red LED turns ON to indicate fault condition.
Once the short circuit is removed, the circuit automatically resets and restores output.

✅ Suitable for:
DC power supply protection
Battery protection circuits
DIY electronics projects
Lab bench power supplies
Student electronics experiments
This is a low-cost, efficient and reusable protection circuit for 5V, 9V, and 12V systems.

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