I will need new plate choke for my project. Due to huge shipping cost involved for 2 pieces of 13lbs plate chokes, i have found a local winder who stock M6 EI silicon steel and is willing to do layer winding.

My requirement is as follow,

1.75" Tongue x 1.75" stack, 50W/500Vrms, 45H, tube operating at 100mA.

I got the size for the choke based on the formula,

VA = (188 x L x I x I) for 60Hz

so

VA = 3 x (188 x L x I x I) for 20Hz

VA = 3 x 188 x 45H x 0.11A x 0.11A = 307 VA

(I = 0.11A instead on 0.1A for some allowance)

So i figured 307VA + stacking factor, a 1.75"x1.75" core size of 340VA should fit the bill.

Can someone tell me how many turns should i be using and what is the airgap per leg on the EI core? What is the flux density distribution involved between the DC and AC element.

I read some books recommending the use of sliding rule with C.R. Hanna curve but can't seem to locate it online. Can someone point me to that?

Or even better, is there free software or spice simulation for DC choke design which i can used for different core size?

Thanks in advance,

Swordsman