The bistander thread

[Turion]

I do not know number of turns per coil. I've never counted that.

http://www.norticinc.com/plastic-spool/

If you look in the far right column and go down to the bobbin that comes 245 to a case, that's the one I am using.
15/16 is the the outside diameter of the "tube" the coil is wound on. 3 1/16 " in length between coil ends. Outside diameter of the coil (wire) I wound is 3".

I will have to run the machine again, get you a screen shot, measure with an RMS meter and get the RPM all at the same time. I did not output full voltage from the coil for the video because all you asked for was a wave form. If full voltage output is important, let me know, otherwise I will basically do what I did before. I might have to reduce some things to get the full wave form on the screen at full voltage output. And it really WON'T be full voltage output since I never run it faster than 2800 RPM, although I have had it up to 4,000 just for fun. It may not be until much later tonight. My wife is working from home today so I try to not run things while she is in the office right next to my shop.

[BroMikey]

This is how I calculate, by averaging. I am not perfect at the end but you get the idea. This one was a 51 strand so 2 extra strands, but all I wanted to find was the general spool size needed

[bistander]

I do not know number of turns per coil. I've never counted that.




If you look in the far right column and go down to the bobbin that comes 245 to a case, that's the one I am using.
15/16 is the the outside diameter of the "tube" the coil is wound on. 3 1/16 " in length between coil ends. Outside diameter of the coil (wire) I wound is 3".

I will have to run the machine again, get you a screen shot, measure with an RMS meter and get the RPM all at the same time. I did not output full voltage from the coil for the video because all you asked for was a wave form. If full voltage output is important, let me know, otherwise I will basically do what I did before. I might have to reduce some things to get the full wave form on the screen at full voltage output. And it really WON'T be full voltage output since I never run it faster than 2800 RPM, although I have had it up to 4,000 just for fun. It may not be until much later tonight. My wife is working from home today so I try to not run things while she is in the office right next to my shop.

Thanks,
If the RMS meter reading appears consistent with the scope we can just use the meter for open circuit voltage on the coil. I would like to get a curve of voltage vs RPM, say using values at 500, 1000, 1500, 2000, 2500 and 3000. As long as you record actual reading for the voltage measurements, the RPM values are targets. Just get close, like 936 is close enough to 1000, but record the exact RPM number. Xcel will smooth out the curve. I guess I'd like to see an expanded screen shot of a single cycle to examine the hash at the peaks and slopes of the rise and fall. Mid range RPM is ok, just record value. Please mark the coil so repeat tests are on the very same coil. I don't see need to go above 3kRPM.

After seeing that no-load voltage vs RPM curve, the same thing tested using a fixed load for comparison will help determine if coil impedance is causing excessive voltage drop.

Then similar tests, no-load and loaded using the 30% longer coil/core should explain why output dropped.

With a magnet (on rotor) TDC over the core, please use your gauss meter on the back end of the core, for both coil/cores. Please use the same rotor magnet for both, as it's possible magnets may differ. Do you have a spare magnet you can measure or reach the face of a magnet on the rotor with the meter probe? I'd like to know how much of the flux goes all the way through the core.

I am fairly certain that the low voltage is due to;
1) low flux, caused by the strange cording (4 poles per coil) or flux leakage.
Or
2) excessive impedance in the coil.
Or
3) combination of 1 and 2.

The series of no-load and loaded generated voltage curves should give the data to tell. And hopefully point towards corrective action.
bi

ps
When you test a single coil/core, are there adjacent or opposite cores in place? Please note if so, or not. Also I think you should test if an opposite mounted core, or adjacent one, affects the flux in the coil/core on test. This should be easily done by checking a few points against the voltage curves. Hate to develop a fix and have it fail because we overlooked something like interaction with other cores. Think about other things which might go unnoticed now but interfere later.

[Turion]

Math. I hate math. I hate it so much I would pay someone to count to ten for me so I don't have to do it.

But, If I wound a single strand of #23 AWG (.0226 DIAMETER) wire around the bobbin and the next layer went directly on top of the first layer....

If we assume the diameter of the wound coil is 3" and the tube that makes up the bobbin is 1" there is 2" of wire.

Since the wire is .0226 in diameter, 2" divided by .O226 means there would be 88 turns of wire if each one was directly on top of the one below it to get from 1" diameter to 3" diameter.

Since the coil is about 3 1/16 of an inch long between the two end pieces, that is 3.0625 divided by .0226 which equals 135.50 winds from one end of the coil to the other to make one layer of wire on the bobbin. So 88 turns high x 135 winds long = 11,880 turns. These coils are not perfectly wound by ANY stretch of the imagination, so I would assume probably 10% MINIMUM loss of winds, if not more. Which would leave 11,762 winds OR LESS on my coils. But someone better at math might have a better way to figure this out. I chose the simplest method I could think of.

[Turion]

Thanks,
If the RMS meter reading appears consistent with the scope we can just use the meter for open circuit voltage on the coil. I would like to get a curve of voltage vs RPM, say using values at 500, 1000, 1500, 2000, 2500 and 3000. As long as you record actual reading for the voltage measurements, the RPM values are targets. Just get close, like 936 is close enough to 1000, but record the exact RPM number. Xcel will smooth out the curve. I guess I'd like to see an expanded screen shot of a single cycle to examine the hash at the peaks and slopes of the rise and fall. Mid range RPM is ok, just record value. Please mark the coil so repeat tests are on the very same coil. I don't see need to go above 3kRPM.


After seeing that no-load voltage vs RPM curve, the same thing tested using a fixed load for comparison will help determine if coil impedance is causing excessive voltage drop.

Then similar tests, no-load and loaded using the 30% longer coil/core should explain why output dropped.

bi, I killed the 30% longer coil. I actually took the core out of it and cut it in half to use in another experiment I am working on. I have no more of that permalloy core material and a new spool is $700.00 so I wanted to use every drop of it. Since the voltage in that coil was SO MUCH less than the old iron core and also far less than the new coil, I saw no value in it. Adding length to the core and more wire was not a solution to my problem. Even if the problem gets fixed, I don't see the coil that was only putting out 14-16 volts suddenly outputting 130 volts. It will be hard enough getting one putting out 96 volts to output 130. The wire I wound onto a large spool so it can be used on other projects.

I could use one of my iron core coils. They do not put out the correct amount on this machine either. I could reduce the windings by 30%, which would be similar to ADDING 30%, if THAT will work. I don't mind ruining one of those coils since I will never use them for anything except projects, and I can always solder the wire back on.

With a magnet (on rotor) TDC over the core, please use your gauss meter on the back end of the core, for both coil/cores. Please use the same rotor magnet for both, as it's possible magnets may differ. Do you have a spare magnet you can measure or reach the face of a magnet on the rotor with the meter probe? I'd like to know how much of the flux goes all the way through the core.

My gauss meter is old and doesn't have a probe. I could stick it in the coil hole next to the rotor, but I wouldn't be able to see the reading. I can order a new one tomorrow as it is the 1st of the month, and I get money the first of every month for stuff. I already have five items in my Amazon cart, so this would make six and that would be the end of my my monthly budget. Not unusual to spend it all the first day. A new gauss meter is $144.00. It would be here Thursday. Let me know ASAP if you need that done and I will order it.

I am fairly certain that the low voltage is due to;
1) low flux, caused by the strange cording (4 poles per coil) or flux leakage.
Or
2) excessive impedance in the coil.
Or
3) combination of 1 and 2.

The series of no-load and loaded generated voltage curves should give the data to tell. And hopefully point towards corrective action.
bi

ps
When you test a single coil/core, are there adjacent or opposite cores in place? Please note if so, or not. Also I think you should test if an opposite mounted core, or adjacent one, affects the flux in the coil/core on test. This should be easily done by checking a few points against the voltage curves. Hate to develop a fix and have it fail because we overlooked something like interaction with other cores. Think about other things which might go unnoticed now but interfere later.

I can run it at the different RPM's with no other coils. Then with coils on both sides, then with a coil opposite it and compare. This is going to be several hours of testing!n I still think it could be that the old machine has N52 magnets on the rotor and this one has N42, but 12 magnets outputting more than 24 really baffles me.

[BroMikey]

I have no more of that permalloy core material and a new spool is $700.00,

I could use one of my iron core coils.

They do not put out the correct amount on this machine either.

I could reduce the windings by 30%, which would be similar to ADDING 30%, if THAT will work.

I already have five items in my Amazon cart, so this would make six and that would be the end of my my monthly budge

Not unusual to spend it all the first day.

A new gauss meter is $144.00. It would be here Thursday. Let me know ASAP if you need that done and I will order it.

I still think it could be that the old machine has N52 magnets on the rotor and this one has N42, but 12 magnets outputting more than 24 really baffles me.

Is that permalloy wire 70/30 or 60/40 or 50/50 iron nickel? No need to spend $700 on the wrong blend.

[Turion]

I don’t remember. I’d have to look at the # on the spool and look it up. We tested several. We order by #. Spool is in Sacramento at my buddy’s place. He will be bringing it out on Friday.

I did ALL the testing today while my wife was at lunch with my camera running so I wouldn’t have to stop and write stuff down and when I got done, my phone had died. Will try again when it is charged.

[BroMikey]

I wouldn’t have to stop and write stuff down and when I got done, my phone had died. Will try again when it is charged.

Let us know. Hear is Permalloy history

http://www.vias.org/albert_ecomm/aec...ation_009.html

[bistander]

Hi Turion,
Been busy all day. Thanks for your reply.
No worry about that 30% larger coil. I thought you had it on hand. And don't bother hacking down another coil, for now.
Do not buy a new gauss meter on my account. Use the one you have on the back of the cores and on a bare magnet if you have one, or on a rotor mounted magnet if you have the rotor disassembled.
I realized that it will be very useful, to take the generated voltage vs ,RPM curves on the 12 pole machine, with the same coil/core, if possible. Same characteristic curve comparing 12 vs 24 poles can tell us a lot. The no-load generated voltage curve is the first test I'd run on every build.
Turns per coil calculations look good except don't forget to divide by 3 due to having 3 wires in parallel. Effectively that is like one third the loops with three times larger wire. The turns/coil is an important number for use in Faraday's equation, and Lorentz, and for inductance.
More later.
bi

[Turion]

I ordered the gauss meter anyway. No way to measure what the rotor magnet is actually putting out to compare it to the other machine without that probe, unless I stick the same bolt on the magnets and measure the flux on the end of the bolt. I'd rather be more accurate and KNOW I have the wrong magnets. Especially since, if I do, I'm going to end up spending close to $1,000 to have a new rotor made and purchase new magnets. I wouldn't like to do that for NOTHING. I'm sure I will use the meter again many times in the future.

Had stuff come up today I needed to deal with, so will get to the testing when I get home tomorrow around 10:00 AM. Have to run to town in the early morning for an hour or so.

[bistander]

Redid turns calculation. The other way. Used to use "LMT" or Length Mean Turn in calculation. That is the average length of one turn of wire. Lots of the coils were not circular. But on a circular coil, it is easy. Outer diameter minus inner diameter times pie. Or 6.28 inches. Total coil wire is 3000 feet. 3000 * 12 / 6.28 = 5732 total turns. Divide by 3 = 1910 Turns/coil effective. You needed to use radius instead of diameter. Also, your wire diameter was likely without insulation (seems really thin, but adds up). Considering connection leads, I'd call it 1900 T/c.
bi

[Turion]

I didn't need to use radius. The distance across a wire is its diameter. The "thickness". I was stacking wire on top of wire in my calculation, and laying wire beside wire. Thickness or diameter is what matters in that calculation. But you were correct about the insulation. AWG # 23 with insulation is .0236 with insulation not 0.022572. So two inches high divided by .0236 = 84, not 88. And 3.0625 divided by .0236 means there would be 129.7 turns on one row, not 135.5. So 84 x 129 = 10,836 turns divided by 3 (you were also correct about that) = 3,612 turns per wire. Minus whatever happens when you don't wind perfectly.

Edit: Typing error, not MATH error. 10,836 turns, not 110, 836 turns.

[bistander]

I didn't need to use radius. The distance across a wire is its diameter. The "thickness". I was stacking wire on top of wire in my calculation, and laying wire beside wire. Thickness or diameter is what matters in that calculation. But you were correct about the insulation. AWG # 23 with insulation is .0236 with insulation not 0.022572. So two inches high divided by .0236 = 84, not 88. And 3.0625 divided by .0236 means there would be 129.7 turns on one row, not 135.5. So 84 x 129 = 110,836 turns divided by 3 (you were also correct about that) = 3,612 turns per wire. Minus whatever happens when you don't wind perfectly.

I was referring to bobbin and coil radii, not diameters. You need to count the wires in the cross section of a coil side. That would be the length times (outer coil radius - inner coil radius) or approximately 3" long by 1" thick.
bi

[Turion]

Wind a flat Tesla coil on a table top with a 1" hole in the center and winding around and around until the coil is 3" across. You would have 84 turns of #23 AWG wire to make that Tesla coil in those dimensions. .
Now if you stack these "Tesla coils" 129.7 high, that is how many would fit on the bobbin between the two ends. So that is 84 turns times 129 of them = 10,836 turns divided by 3 wires or 3,612 turns, and that is NOT a very tightly wound coil, so the number might be higher. Winding a coil tightly by hand isn't realistic EITHER. But basic math says it MUST be more than 1900 turns per wire. Somewhere between that and 3,600 That's a HUGE difference.
See drawing:

EDIT: Oh, I got it. I see what you are saying. I have my dimensions in my drawing wrong. Not two inches wide on each side of the barrel, but 1 inch wide om each side of the barrel. Duh! So divide my number by 2 and it is in the ballpark with what you are saying is the correct winding. Sometimes it takes me a while to have things sink in


coil images.jpeg

[Turion]

I made a video of the whole test, so here it is as well as the numbers

RPM Volts
500. 43
996. 85.7
1505. 129
2004. 172
2513. 217
3008. 262

Video of testing:

https://youtu.be/w1-9ZSVE5S0

Open voltage at 2500 RPM is over 100 volts greater on these same coils with the old clunker machine. closer to 150 volts greater.