coil for delta pulse

[maximimus]

hello all

many people built small coils

but not much information on large and medium-coil

can you help me to reel 60x60 and 80x80 with cable and enameled wire of 0.5

Notice to contruction which is managed for you

thank you for all your help

[berreizeta]

PI coils

try:

http://www.66pacific.com/calculators/coil_calc.aspx

60cm dia. = 188.5cm circ. x 22 turns = 41.47mts = 4uH

[Qiaozhi]

try:

http://www.66pacific.com/calculators/coil_calc.aspx

60cm dia. = 188.5cm circ. x 22 turns = 41.47mts = 4uH

There's definitely something intuitively wrong with that calculation. 22 turns is high for such a large coil, and the inductance cannot possibly be as low as 4uH.
For a 300mm radius coil with 22 turns of 0.5mm wire, the inductance should be just over 1mH.
A total of 14 turns will give 442uH, which is a more sensible value.

[berreizeta]

COILS

GOOD CALCULATOR !!

THANKS.
GER.

[Qiaozhi]

GOOD CALCULATOR !!

THANKS.
GER.

You can download it here (double-click on coilcalc.htm to start the program) ->

[berreizeta]

COINS CALCULATOR

A MILLION THANKS


GER.

[porkluvr]

There's definitely something intuitively wrong with that calculation. 22 turns is high for such a large coil, and the inductance cannot possibly be as low as 4uH.
For a 300mm radius coil with 22 turns of 0.5mm wire, the inductance should be just over 1mH.
A total of 14 turns will give 442uH, which is a more sensible value.

Hoorah. Man, these powers of ten and coil calculations are causing trouble over and over again.

[bbsailor]

Hoorah. Man, these powers of ten and coil calculations are causing trouble over and over again.

Porkluvr and all interested,

I'll add one more thing to consider when calculating coil inductance.

The wire insulation thickness determined how far apart the conductive wire lies in relation to the actual space between windings. More space equals less inductance.

Here is a little trick to better estimate the wire bundle diameter which can be input into a coil calcutalor to more accurately calculate a PI coil inductance.

Multiply the coil wire OD by a constant of 1.155, multiplied again by the square root of the number or coil turns. This will give you the coil bundle cross-section diameter. Enter this number into a multi layer coil calculation with the diameter being the length and height to the input of the calculator.

Teflon has the lowest dielectric, so a thinner Teflon insulation thickness can give a similar results as a thicker higher dielectric insulation such as PVC.

The consequence of using a thicker wire bundle is that the circumference of that wire bundle will have a higher coil-to-shield capacitance due to the higher surface area.

The wire diameter, insulation thickness, insulation dielectric and coil construction technique (space between the wire bundle and shield) will have an impact on the speed of the coil due to the value of the damping resistor (Rd) needed to damp the flyback oscillation. Less capacitance in the TX circuit means that Rd can be higher and allow the coil to be critically damped to allow faster sampling.

In mono coils some techniques that allow for faster sampling include:

Choosing low dielectric coil wire insulation.
Spacing the shield away from the coil wire.
Inserting a diode between the MOSFET and the coil to isolate the MOSFET capacitance (COSS) from the TX circuit.
Using the lowest capacitance coax lead and the shortest lead length to minimize capcitance in the TX circuit.


Each of these by themselves helps and is OK, but by using all of them aggregriates these into the full benefits for faster potential sampling.

Homemade one-off coils tend to need some fine tuning to be optimal. A variable damping adjustment with a 1200 ohm, 0.5 to 1 watt Rd with a 5K ohm pot in series with a 1200 ohm limit resistor (all in parallel with Rd) allows you to adjust Rd in the range of 600 to 1200 ohms for designs similar to the Hammerhead. You do not want too much power going through the variable pot as it will arc with the high flyback voltage. You can rescale this method to fit the range of your own PI design or commercial Rd value that you are attempting to match.

At low delays near 10us and below the eddy currents generated in the actual coil wire can cause the coil to be detected as a target. That is why tin-plated stranded wire is better than silver plated stranded wire. Generally, you want the strands to be AWG30 or thinner in size to minimize this from happening.

I hope this helps.

bbsailor

[kt315]

You can download it here (double-click on coilcalc.htm to start the program) ->

hello Qiaozhi. can you do same for square coil? or. what coefficient I must use to convert round coil data in square one?

TIA
Anatolij

[Qiaozhi]

hello Qiaozhi. can you do same for square coil? or. what coefficient I must use to convert round coil data in square one?

TIA
Anatolij

Have a look at this ->
http://www.technick.net/public/code/...uctance_square

If you can build some coils using this calculator and confirm the accuracy of the results, I will create a standalone version.
However, looking the formula, I suspect it's going to over-estimate the inductance value.