guys what will be the inductance of a solenoid inductor if : 1)5 turns 2)4mm internal diameter 3)5mm length of the wire!please help me guys!

 

Hello,

Take a look at this page:

http://info.ee.surrey.ac.uk/Workshop/advice/coils/air_coils.html

The value will be 57.9 nH.

Bertus

 

but please tell me the value of that inductor!

 

Google "inductor calculator"

 

but please tell me the value of that inductor!

Take your values that you have there, and enter them in this calculator and it will give you the inductance.... there i did the googling for you, now, just enter the values and get your answer.....

http://www.daycounter.com/Calculators/Air-Core-Inductor-Calculator.phtml


My .02

 

but please tell me the value of that inductor!

Hello,

Take a look at this page:

http://info.ee.surrey.ac.uk/Workshop/advice/coils/air_coils.html

The value will be 57.9 nH.

Bertus

It appears to be answered in the post above yours.

 

Actually, a critical element has not been provided; that's the size of the wire used.

If AWG 21 wire is used, inductance will be about 122nH
If AWG 30 wire is used, inductance will be about 102nH
If AWG 40 wire is used, inductance will be about 99nH.

 

guys u told the inductance will be 57.9nH ,but can i use #18 copper wire to make that inductor!

 

guys u told the inductance will be 57.9nH ,but can i use #18 copper wire to make that inductor!

Naturally, that formula only works if the diameter of the wire is less than the center-to-center turns spacing. (In a similar vein, I learned the hard way that certain antenna modeling programs "puke" if you try to have two elements occupy the same space....silly me!)


Hmmm....I'll have to consult my wire gauge to diameter conversion chart to see if I can answer the lad's question directly. Please stand by.


Eric

 

i am really thankful for r interest!thank u very much!

 

i am really thankful for r interest!thank u very much!

No problem...I've been winding coils since I was 8. By the way, if it turns out to be mechanically impossible to wind a given coil with that particular gauge wire, you can always twiddle the diameter or the length, or number of turns, as long as the end product is the same. There IS a magic optimized proportion for a coil...that is, the diameter/length/turns ratio that gives you the MOST inductance for a given length of wire. This will also result in the highest Q possible for a solenoid. I forgot the name of this type coil, but there are on-line cackle-ators for that as well.

Eric

 

Hmm,

Bertus came up with very different results than I did; his was around 57uH, but by my calculations it would be in the 100uH range, depending on inductor wire size.

AWG 21 is about the limit for wire diameter, if you wish to keep the coil within the length constraint specified (5mm).

 

wht if i use AWG 18 to make that inductor,what would be it inductance

 

wht if i use AWG 18 to make that inductor,what would be it inductance

The coil length would be over 5mm, so it couldn't be made with 18 Gauge wire.

--ETA: 18ga wire, solid, with insulation is 1.2mm Diameter, 5 of them next to each other would be 6mm long.


Smallest, using 20 Gauge insulated wire, 100% fill


Coil length: 5 mm
Avg. coil diameter: 4.9 mm
Winding thickness: 900 µm

Wire length: 82 mm
Resistance: 2.2 mohm (copper wire at 20°C))

5 Turns, 5mm long, 4mm inside diameter.
Inductans: 71.34 nH
Using a different gauge wire will change the calculation GREATLY when working with these small values.

 

Hello,

I used the formula from the page I gave before:

The single layer coil

A single layer coil has two advantages. Firstly, like all air core coils, it is free from 'iron losses' and the non-linearity mentioned above. Secondly, single layer coils have the additional advantage of low self-capacitance and thus high self-resonant frequency. These coils are mostly used above about 3 Mhz.
In the simple case of a single layer solenoidal coil the inductance may be estimated as follows (Wheeler) -
L = 0.001 N2r2 / (228r + 254l)
Equation ACS



where L is the inductance in henrys, r is the coil radius in metres, l is the coil length in metres (>0.8r) and N is the number of turns.
This formula applies at 'low' frequencies. At frequencies high enough for skin effect to occur a correction of up to about -2% is made.
To construct a self-supporting air cored coil take a length of plain 1 millimetre diameter copper wire and hold one end in a bench vice. Take the other end in a pair of pliers and pull until the wire has stretched slightly - this will straighten it. Using a 5 millimetre diameter drill bit wrap the wire around it until enough turns have been applied. Using 'long nosed' pliers bend the ends of the coil to get them into a radial position.
Small reductions in the inductance obtained can be achieved by pulling the turns apart slightly. This will also reduce self-resonance. Other combinations of wire and coil diameter may be tried but best results are usually obtained when the length of the coil is the same as its diameter.
This property also leads to a disadvantage of the air cored coil: microphony. If you need good frequency stability in the presence of vibration then wind the coil on a support made from a suitable plastic or ceramic former.

Greetings,
Bertus

 

is it better to use insulated copper wire to make LC circuit or a non-insulated one!

 

is it better to use insulated copper wire to make LC circuit or a non-insulated one!

It must be insulated for this size, preferably "magnet wire", which has an enamel coating rather than the plastic sheath.

Using a thicker insulation will change the length of the coil, and therefore the inductance. This is the reason that the calculations above do not match, or are given as a range. My estimate assumes the wires are wound next to each other, with insulation touching (100% fill factor).

If the coils may be in contact with each other, or any other items in the circuit, insulated wire should be used.

Some high power transmitters have non-insulated inductors, but those are kept from being easily accessed or touched.

 

should i leave gap in between the woundings to make solenoid inductor like this: "http://www.flickr.com/photos/aj_silverthunder/4098212631/ "
or should i not leave any gap between them..

 

If you are using wire larger than 22gauge, there won't be any room to wind the coil within the dimensions you specified.

 

is it better to use insulated copper wire to make LC circuit or a non-insulated one!

This depends on the frequency. If it's a UHF circuit, you will be better off with fat, uninsulated conductors...as long as the spacing between turns is sufficient to hold off the voltage.


Eric