Project: Transformer Checker

[Cool_buddy_57]

Yes i like it but.
What is the neon bulb?
A neon bulb mean LED or any thing else

 

[Nigel Goodwin]

Yes i like it but.
What is the neon bulb?
A neon bulb mean LED or any thing else

It means a 'neon bulb', it's a very common old component, they require a high voltage (about 70V to 90V to strike) - nothing else will do. If you really can't find one, try old switched mains sockets, those that have a red/orange light, they use a neon bulb.

 

[philba]

maybe this is a dumb question but how often do transformers fail with a short inside the coils? I guess if they really got cooked and melted the insulation on the wires it could happen but wouldn't that be pretty obvious from a visual inspection?

 

[Nigel Goodwin]

maybe this is a dumb question but how often do transformers fail with a short inside the coils? I guess if they really got cooked and melted the insulation on the wires it could happen but wouldn't that be pretty obvious from a visual inspection?

It's a common failure mode, particularly in line output transformers, but also in modern cheap mains transformers - however, modern transformers usually have internal (non-replaceable) heat fuses, and the heat generated by the shorted turn will usually blow the heat fuse.

 

[Cool_buddy_57]

It means a 'neon bulb', it's a very common old component, they require a high voltage (about 70V to 90V to strike) - nothing else will do. If you really can't find one, try old switched mains sockets, those that have a red/orange light, they use a neon bulb.

Ok Dear u say Right
But u say that neon bulb require 70V to 90V to stike. And in transformer checker circuit 6V battery is used. What u saying about this?

 

[Nigel Goodwin]

Ok Dear u say Right
But u say that neon bulb require 70V to 90V to stike. And in transformer checker circuit 6V battery is used. What u saying about this?

That's the entire point behind the project!, when the current is discontinued a high back EMF is generated, it's that high voltage that causes the neon to strike. If there's a shorted turn in the transformer this will damp the back EMF, and the neon won't light.

 

[jkr6211]

hi

simple way to test your transformer :lol:

very ingenius method

 

[Speakerguy]

The transformer will easily create a high voltage pulse and light the LED/neon bulb when you release the switch.

I had a transformer with a 1mH coil that I was switching with a MOSFET (ignition coil primary) that was being charged with 12V. The voltage spike at the drain of the low-side-switch n-channel mosfet was >200V.