What is the diameter of a ball pen ?

[Rfmhz]

I've built this project ,that describes a coil diameter of a ball pen that is wound . Can anyone tell me the diameter of it ?

 

[Joe G]

my basic cheapo plastic "clicker type" has a outside diameter of exactly 0.125 inches. that is the tube that holds the ink and goes through a spring.

 

[alec_t]

Pens come in various diameters. Ask the author of the project article.

 

[Brevor]

He means an ordinary ball point pen, about 3/8" in diameter. It's not critical just wind your coil on a 3/8" or 5/16" drill bit. The final inductance can be adjusted by spreading or compressing the coil.

 

[atferrari]

What does refrain yourself from googling on this? So simple.

 

[dr pepper]

Mines 8mm, very close to 5/16".