A Revised Inductance Calculator

For curiosity, as a reel of bare wire was next to the keyboard, wound a random coil on a pencil ... (equiv') 25Awg, 0.833" long, 0.328 diameter, 12 turns pulled out to that length. Measured as 1.0uH (GenRad 1685 digital Impedance meter). The L calculator said "0.5uH". Was going to whinge but have just found my sodding LCR meter is faulty. Yes, your calculator works well ;) regards john

.03uH coil - rounds to .1uH (.0001mH)

mike

why not add core permeability input and std core dropdown/combo?

the LC calc... a designer would want to know what cap to use for given L and f or what L for given C & f. my programs use a "solve for" check box next to the text inputs.

nice wind chill charts, i think. i have this nomogram, but it calculates comfort level. any idea how that corresponds to temp?

mike

is that achived at google? if so, what's the subject line to search on.

mike

BTW love the book, if i haven't already told you directly.

Capacitance-Frequency-Inductance CALCULATOR

also... Voltage-Current-Resistance-Power CALCULATOR Resistance-Frequency-Capacitance CALCULATOR dbm-Voltage-Impedance CALCULATOR Zener Voltage Regulator CALCULATOR Loan-Monthly Payments CALCULATOR

How do you define 'length' of a coil?

Is it the axial distance between the two extreme ends of the wire, or is it the distance between the wire centres at the ends of the coil? Or is it the number of turns times the winding pitch.

Or what is it? It matters when there are not many turns.

What do Grover, Wheeler, etc., have to say about it?

---- Reg

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On 30 Jul 2003 18:33:47 -0700, Winfield Hill Gave us:

Grab the source from his calculator.

On Thu, 31 Jul 2003 02:09:37 GMT, Active8 Gave us:

That's just it. Ten turns of wire bears out a different inductance, and the difference is the core configuration!

Also making the same inductance across ten different core types will make ten equal value inductors, but they will all perform entirely differently one to another. Raw sines are one thing, but complex waveforms behave differently than the simple LCR bridge stimulus.

Hi Mike, Pretty Small Coil. Yes, this is due to Rounding. I can fix this, but even if I change this, the next person will come up with a .003 uH coil, or even smaller. How small should I go?

Take care.......Gary

thanks. i really don't need any calculators. i write my own. i'm just looking around for different L calc to compare to another program, the accuracy of which is suspect.

that loan calc...

i used a loan pmt formula out if a TI calculator book once when i was

1. and when i went to the bank for a loan for my first car, I found out that the bank didn't calculate payments based on that formula.

mike

i'd like to know, too. how long is a 1 turn coil?

wouldn't the center to center distance be the same as N X pitch ?

mike

if you can read JS.

This somehow didn't get attributed, but it was written by Win Hill:

I've put in some likely keywords and got topics with subject lines of "If I only had a brain" and "tomato launcher" which Win participated in back in 1977. I've only been a semiregular here for a year or two, looks like I missed a lot of good threads.

Megaditto's. [I gotta stop listening to talk radio]

heh, heh. that's two of us. NGs turn up some funny stuff at times. I'm hoping Win will come back and zero me in on that thread.

mike

I never heard anyone ask this question before. The Length of the coil is the "MEASURED LENGTH of the windings, END TO END". For this calculator and any other formulas (I have seen) to work accurately, All layers must be equil length.

Take care.....Gary

I have a program that works quite well from very tiny to quite large. After all, it's just scaling, ummm?? Anyway, it happens to make it easy to do coils down in the 0.05" diameter region, and they are sometimes useful. Just wind some wire on a small machine screw; it will typically hold its shape well when you unscrew the screw from it.

When I have some time I might try comparing your web script with a program I've learned to trust. No time right now. Does yours give the equivalent capacitance and self-resonant freqs for the first parallel and first series resonances? How about Q at some input frequency? Those are useful.

Cheers, Tom

That sinking feeling you get when you realize that you have just farted in public :-)

Quite Simply, a one turn coil is equivalant to the diameter of the wire you are using.

Take care.......Gary