ETFE wire

[lmrubin]

Hi... I just found a bit of 30 AWG ETFE "triple insulated wire (remington brand). Would this be of any value for making a pi mono coil?

[bbsailor]

The ETFE insulation has a 2.6 dielectric constant which is low and good. The AWG 30 wire is thin enough to not hold many eddy currents and could allow early sampling with a lower delay. The triple thick insulation would hold the coil turns farther apart and cause to coil to have a slightly lower inductance than wire with a thinner insulation. You might need to add an extra turn or two to get the desired coil inductance. A 10 inch diameter coil might need 20 turns to get near 300 micro henries inductance. The value of the damping resistor to damp coil oscillations will be higher with less capacitance as seen by the coil and this is good for making a fast coil. The AWG 30 wire should be used by a mono PI detector operating at a higher frequency and requiring less coil current.

Taking all these things in consideration, make the coil and let us all know how it works out.

Joseph J. Rogowski

[Matt_Rowe]

just bought some remington wire,22awg,made a 9 inch coil, 280 mh, 1.1 ohms resistance,
Tried to follow your fast coil build bbsailor

[Matt_Rowe]

after tightening up with electrical tape
.320 mh
1.1 ohm

[bbsailor]

just bought some remington wire,22awg,made a 9 inch coil, 280 mh, 1.1 ohms resistance,
Tried to follow your fast coil build bbsailor

[ATTACH]53470[/ATTACH]

Matt,

I believe your coil is 280 micro Henries or uH. Making a fast coil requires doing a collection of things that all point in the same direction to allow the coil to see lower capacitance within the coil windings, coil to shield capacitance, MOSFET COSS or output capacitance, coax wire capacitance that connects the coil to the PI circuit board. When a coil sees less capacitance a higher value of damping resistance can be used because there is less energy in the flyback pulse oscillations that can be damped quicker thus a faster coil.

When you are able to get the delay below 10 uS, you need to be sure that the coil wire is not retaining any eddy currents beyond your desired delay time as at minimal delay settings the coil wire might be seen as a target if it holds eddy currents too long.

Try to use a polyethylene spiral wrap on your wire to keep it tight and try to use Scotch 24 wire mesh in a single layer around the coil. Do not overlap the wire around the cross section of the shielding wrap to prevent any eddy currents from developing in the shield wire itself. If you do overlap a little, just place a layer of electrical tape over it to prevent forming a conductive loop. Just leave a shield space where the coil wires enter and exit the coil winding.

What PI machine is the coil planned to be used with?

Joseph J. Rogowski

[Matt_Rowe]

Thanks joseph, i was going to use plastic wrap next, and then the scotch 24 tape with a space between so as not make a short,
it is going on a surf pro, the square board, not the 1.2 from andy. still have to read your pdf as building my coil.

[lmrubin]

The ETFE insulation has a 2.6 dielectric constant which is low and good. The AWG 30 wire is thin enough to not hold many eddy currents and could allow early sampling with a lower delay. The triple thick insulation would hold the coil turns farther apart and cause to coil to have a slightly lower inductance than wire with a thinner insulation. You might need to add an extra turn or two to get the desired coil inductance. A 10 inch diameter coil might need 20 turns to get near 300 micro henries inductance. The value of the damping resistor to damp coil oscillations will be higher with less capacitance as seen by the coil and this is good for making a fast coil. The AWG 30 wire should be used by a mono PI detector operating at a higher frequency and requiring less coil current.

Taking all these things in consideration, make the coil and let us all know how it works out.

Joseph J. Rogowski

Just as a follow up...
I used the coil calculator, and input the diameter of the wire ONLY, not including the insulation (although now I'm reading that some people are saying I should include the insulation). I have a shell from Mr. Bowers that's close to 8" and planned to fit the coil inside. Anyway, what I currently have is a coil about 22 turns. I don't have an inductance measuring tool (although I'm waiting for an inexpensive lcr I bought on Aliexpress), so the only thing I know of that I can do is to measure resistance, and also to see if the coil works! The coil seems to work - picks up my hand with a thin wedding band at least from about 5-6". But the resistance seems high to me - it measures about 5 Ohms; the ones I made from magnet wire are only 1.5 Ohms. I'm not sure what to do at this point...I don't want to burn it out. I guess I'll check the calculator again with the total diameter of the wire... If anyone has any suggestions I'm all ears...

[6666]

Just as a follow up...
I used the coil calculator, and input the diameter of the wire ONLY, not including the insulation (although now I'm reading that some people are saying I should include the insulation). I have a shell from Mr. Bowers that's close to 8" and planned to fit the coil inside. Anyway, what I currently have is a coil about 22 turns. I don't have an inductance measuring tool (although I'm waiting for an inexpensive lcr I bought on Aliexpress), so the only thing I know of that I can do is to measure resistance, and also to see if the coil works! The coil seems to work - picks up my hand with a thin wedding band at least from about 5-6". But the resistance seems high to me - it measures about 5 Ohms; the ones I made from magnet wire are only 1.5 Ohms. I'm not sure what to do at this point...I don't want to burn it out. I guess I'll check the calculator again with the total diameter of the wire... If anyone has any suggestions I'm all ears...

The thinner the wire the higher the resistance depending on the length, turns etc, but I've done a quick calc based on an outside wire dia of .68mm, 8 inch, 22 turns, calcs to about 270uH, so close enough for testing.
Out of all the dodgy cheap LCR meters I have found the LC200A Rev 5.5 to be fairly accurate if you calibrate it correctly, they can measure to within ~ + or - 20-30 uH compared to my DE5000.
+or - 20-30 uH is less than one turn so close enough, you MUST calibrate every time you switch on the LC200A to keep it accurate.
For a 300uH coil ( that's about as high as I go)
1. switch on with good charged battery's
2. select HI L
3. short leads together
4 push ZERO calibrate button and wait till it saves data
5 measure coil

[lmrubin]

The thinner the wire the higher the resistance depending on the length, turns etc, but I've done a quick calc based on an outside wire dia of .68mm, 8 inch, 22 turns, calcs to about 270uH, so close enough for testing.
Out of all the dodgy cheap LCR meters I have found the LC200A Rev 5.5 to be fairly accurate if you calibrate it correctly, they can measure to within ~ + or - 20-30 uH compared to my DE5000.
+or - 20-30 uH is less than one turn so close enough, you MUST calibrate every time you switch on the LC200A to keep it accurate.
For a 300uH coil ( that's about as high as I go)
1. switch on with good charged battery's
2. select HI L
3. short leads together
4 push ZERO calibrate button and wait till it saves data
5 measure coil

Thanks. The lcr I bought is this one:
https://www.aliexpress.com/snapshot/...Id=32829577952

But I'm not sure what that all means with regards to the resistance being at 5ohms...Isn't that too much? I don't want the mosfet or anything else to burn out...I'd like to aim for a semi-fast coil, and I would think that using this wire isn't going to get me there...? Wondering if I should go back to the magnet wire...