Light Bulb Current Limiter \ Dim Bulb Tester

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🟨🟨🟨 WARNING – HIGH VOLTAGE 230 V! 🟨🟨🟨
🟨 RISK OF ELECTRIC SHOCK AND FIRE 🟨 

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This project presents an enclosure designed for a simple light-bulb current limiter, used for service and diagnostic work on devices powered from the 230 V mains supply.

The enclosure consists of two halves fastened together with M3 screws (10 mm length), threaded into heat-set M3 threaded inserts, which allows for a durable and repeatedly re-assemblable construction.

In typical use, the light bulb is connected in series with one of the supply conductors (commonly referred to as L), while the second conductor (N) is routed directly to the output socket.
To ensure that the bulb is connected in the phase conductor (L), a three-pin connector salvaged from an old power supply was used.

The bulb must be a traditional incandescent bulb with a tungsten filament.
In this setup, a 100 W bulb was used.
LED bulbs cannot be used in this application.

The bulb acts as both a current limiter and a visual indicator:

• bright light → short circuit or overload
• dim light or no light → normal operation of the tested device (no short circuit)

The project does not include an electrical schematic and is not a complete device — only the mechanical enclosure is provided.
If you do not know how to properly connect this type of circuit, you most likely should not use it.

⚠️ Responsibility and safety

• The project is intended for educational and service purposes only

• No certification – this is not a protective device

• The author takes no responsibility for:

  • personal injury,

  • electric shock,

  • equipment damage,

  • improper use

• You use this project at your own risk

• If you have no experience working with mains voltage – do not use

📦 Parts list

 Used components:

• E27 light bulb socket
• Tungsten incandescent bulb 230 V / 100 W
• 230 V output socket
• Power cable
• Three-pin connector (e.g. salvaged from an old power supply) The opening size for the 3-pin plug is 31.7 mm × 27 mm.
• M3 × 10 mm screws
• M3 threaded inserts for plastic

Translated from Polish to English using ChatGPT. Due to differences in language and technical terminology, minor translation inaccuracies may occur.