Building a dim bulb current limiter

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briesmith

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I have built a dim bulb current limiter in the usual configuration. (See attached PDF).

The earth wire (ground or CPC) runs from the earth pole on the mains switch via the earth pole on the lamp socket and onto the earth tag on the output socket (outlet).

The neutral wire runs from the neutral pole on the mains switch directly to the neutral pole on the output socket.

The live wire runs from the live pole on the mains switch through the neutral and live poles on the lamp holder and onto the live tag on the output socket.

The bypass live wire runs from the neutral pole on the lamp holder through a simple on/off switch and back to the live pole on the lamp holder.

I want to use a 220VAC neon indicator to show when the bypass has been enabled (ie circuit isn't being limited) but find that when I put a lamp (bulb) into the system, the neon lights up even though the bypass is switched off.

Where should I connect the two poles of the neon indicator lamp to stop this happening? (Can I stop it happening?)
 

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  • 2023_09_09 17_39 Office Lens.pdf
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Connect the neon across the bulb.
There will only be significant voltage across the bulb when there is a load taking a reasonable level of current.

The neon should be effective with a large enough load connected for the lamp to be working as a current limiter.
 
The problem is that with no load in the socket, the bulb won't be limiting the current as there is no current to limit, so the voltages will be the same with the bypass enabled or not.

I would just use a two pole switch for the bypass. Use one pole to bypass the bulb, and one to light a neon, or any other warning device you want. With a separate pole, you can make that warning as obvious as you like.
 
Thanks everyone for your help. Been on holiday hence the tardy reply. I am going to try Lightium's solution and I'll let you know how that goes. Again, thanks for your interest.
 
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