Thread: Household light globes

Originally Posted by Blknight.aus

the nichrome wire glows quite nicely.

Oh. Didn't know that..

Originally Posted by Blknight.aus

if your dull bulb tester works like I think it does, you can also use nichrome wire and old school carbon heater elements.


The nice thing about using the nichrome wire is its easy to position the wire mounts to account for the varying required wattages then clip your load onto the required point.

It doesn't work like you think it does. An incandescent light bulb does not have a constant resistance. It's like an extreme PTC thermistor. When the filament is cold there's almost no resistance, and as it starts to warm up the effective resistance increases exponentially. This limits the current available to the load in series with the bulb and gives the "bulb is bright, we have a problem" indication. You can not do this with any form of fixed resistance..

John just use Osram halogen replacement incandescent bulbs, they work fine and are available at Bunnings.

Originally Posted by BradC

It doesn't work like you think it does. An incandescent light bulb does not have a constant resistance. It's like an extreme PTC thermistor. When the filament is cold there's almost no resistance, and as it starts to warm up the effective resistance increases exponentially. This limits the current available to the load in series with the bulb and gives the "bulb is bright, we have a problem" indication. You can not do this with any form of fixed resistance..

John just use Osram halogen replacement incandescent bulbs, they work fine and are available at Bunnings.

Thanks for the explanation. Again. Yes, I will.