26" wheel won't "Gear Change" without moving the coil away

[jelloir]

I recently replaced a 20" 17 magnet wheel with a 26" 21 magnet wheel on 7 transistor SSG using the same magnets (from Teslagenx). The SSG won't change up to single spike per mag unless I push the coil away and let the RPM build up, once past the threshold it will be fine and I can bring the coil closer again to where it seems to run the best at about 9.5mm (3/8). It's not a major issue as the coil sits on an adjustable platform, but eventually it will bug me.

The 20" wheel would change up fine. Why would this occur with the 26"? Does my SSG base resistance need to be a little higher? Rheostat's are expensive!

And wow, I'm amazed how much the tiniest change to the coil gap affects the machine. I have nylon screws to adjust the coil platform and quarter or half a turn (half a millimeter or so) is enough to see a difference in charge on my CBAIV.

Edit: I have one spacing between magnets that is about 5mm different than the rest, could this affect it that much, it does kind of do a "chug, chug, chug" thing until I make it switch up.

Thanks

[BobZilla]

Hi James,
You could put a pot in there but you said you don't want too. Another solution may be to put a double throw switch for your resistance, have a slightly lower one on one pole to get her spinning good then throw the switch to the other pole for your preferred running resistance.

The odd ball magnet should not really cause problems since it is a single coil machine, if you had two then you might get into trouble.

[Tom C]

I assume you are running in attraction mode...... that being said you are seeing the side effects of an electromechanical device. "shifting gears" is a well known phenomenon with rotored SG machines. 5 MM spacing is almost 3/16 of an inch, try and correct that....... it should not chug at all... also your freespin time should be hi above 8 minutes. make sure everything is north out... that will cause a chug also if one magnet is wrong, ust a thought.

with more magnets you also get more current into the trigger for the same rpm, if you leave the coil gap farther out will it stay at single pulse? the base may be opening too much at your double pulse, but as your speed goes up the time over the core decreases and switching becomes faster.

Tom C

[jelloir]

Not opposed to getting a rheostat on there, just didn't expect them to be around $100. Would something like this be suitable http://au.rs-online.com/web/p/rheostats/7887826

SSG is running in attraction mode and I had verified magnets are all north out. I will reposition the magnets to get rid of the odd gap and retest it. Freespin was 7:46 without magnets attached to the rim, I'll do an updated test when I remount the magnets. I should buy stocks in 3M.

I had 23 50m x 20m x 10m magnets on there before I put 21 of the original recommended magnets on but I didn't realize the SSG wasn't switching up so never got to test performance with those magnets.

Thanks for the help, the more I get into this the more I realize how little I know

[jelloir]

... With the free spin thing... Is this just based on best effort slinging it with your arm? My 26" wheel gets over 300RPM from the coil/magnets, I'll have to renew my gym membership to get my arm to do the same.

So what is the method for free spin testing?

[guyzzemf]

jelloir
if magnet spacing is off the balance is off .if you balance so there is no rocking when it stops spinning it will be better every where
spin time, shifting [changing pulses per magnet pass] cop ,rpm
guy

[guyzzemf]

jelloir move the coil out the way so the magnets are not slowing wheel nothing should be slowing down wheel, fan ect
spin by hand and time
this is a good time to balance the wheel, as wheel slows and starts to rock the heavy side will end at the bottom add small weight to top ,i use wax repeat until there is no rocking it will make a difference

[jelloir]

Thanks Guy, My wheel is balanced using pieces of lead on the spokes after the magnets are mounted and doesn't rock when up to speed, I'll remount everything as accurately as possible and then do a free spin test again sans coil. I read on another thread that John K was getting 52 minutes free spin, holy crap!

[guyzzemf]

the rocking is when the wheel stop spinning and coil removed
John k 52 min free spin is great. can you imagine how efficient that is
me 14 min 16 mag 27 in . a ssg with a 5 min free spin to a ssg with a 15 min are two different puppies even if everything else is the same

[Tom C]

Not opposed to getting a rheostat on there, just didn't expect them to be around $100. Would something like this be suitable http://au.rs-online.com/web/p/rheostats/7887826

SSG is running in attraction mode and I had verified magnets are all north out. I will reposition the magnets to get rid of the odd gap and retest it. Freespin was 7:46 without magnets attached to the rim, I'll do an updated test when I remount the magnets. I should buy stocks in 3M.

I had 23 50m x 20m x 10m magnets on there before I put 21 of the original recommended magnets on but I didn't realize the SSG wasn't switching up so never got to test performance with those magnets.

Thanks for the help, the more I get into this the more I realize how little I know

you can find a 10 watt potentiometer... you dont need a huge rheostat....

tom C

[wild weasel]

i use these guys
http://www.conrad.be/ce/nl/product/4...f=searchDetail

work good and give me no trouble

[wild weasel]

by the way

are those things so expensive overthere?
i can get a 60 watt variant of yours for 30euro

[jelloir]

I have the 26" wheel back on after repositioning all 21 magnets as close to perfect spacing as I could and rebalanced the wheel. I was able to get 15 minutes free spin time with magnets mounted which gave about 200RPM to the wheel to start with. When running on the SSG it's around 300RPM.

Performance has improved, the gear change still won't happen if the coil is to close, however the distance at which it will has decreased. The SSG makes more of a purring sound now and emmit's a sort of faint ringing noise.

Interestingly when I use my comparator I have to shorten the pulse time to get it to gear change, whereas on a 20" 17 mag wheel I had it was the opposite? Whilst I mention the comparator, I was under the impression from the SSG intermediate handbook that performance would be better than radiant mode, but on my SSG radiant seems much better performing?

I keep reading that there is no sweet spot in attraction mode, but then see people using variable resistors when running in attraction mode, What gives?

[BobZilla]

James I do not have a comparator like yours (have said that already) BUT I do have a lot of experience with cap dumps. Part of what you are experiencing will be because of the changing impedance on the cap.

I used to tune mine sometimes where I would shift between spikes simply because of the cap filling and dumping. Caps can become sort of a moving target to tune too, their voltage is up/down and so is the impedance so if you listen carefully to your coil you may hear pitch differences like up and down. If you get a radio and tune it on AM in a dead spot you may hear better what is happening.

Anyway I am only trying to make you aware that cap's behave much differently than batteries as a load and that may be causing you some confusion in the tuning area.

P.S
Still blurry eyed having my coffee, hopefully I make some bit of sense.

[Branch Gordon]

I'll share what I have seen in attraction mode. As you know, as you adjust the potentiometer the SG "shifts" gears. These are the points where on an oscilloscope or a timing light you see it going from 1 spike, to 2, or 3, or wherever you have it adjusted to. S o let's say on the POT that you have it tuned to 1 spike, but right on the edge to where if you adjusted the resistance any further you would be at 2 spikes. Even though you are increasing the resistance moving down to 2 spikes, you end up with higher current draw and output when you slip from that 1 spike point into 2 spikes. But each spike has a window you can move up and down in. So I can keep raising the resistance inside the 2 spike window, and get the current draw back down. As your primary battery drops in voltage, those switching points change and you can sometimes slip from one window to the other...so you have to make that adjustment to stay in whatever spike range you want at the lower primary voltages. I'm not sure if I did a good job explaining this...let me know if you understand.

The other thing is that you don't want to use current to charge with. So if you are tuned to 1 spike and charging a lawn/tractor battery, and just blasting it with current, you aren't experiencing the full benefit of charging with voltage potential from the spikes. So you need to dial it down until you can still charge the battery up, but with less current. I can charge up my current battery with 260mA, and also with 130mA. I understand there is a balancing act between time and efficiency, but you get what I am saying I think.

The other thing to consider is that there are definitely points where interesting things happen. See this post I made awhile back: http://www.energyscienceforum.com/sh...ll=1#post11909

So that's in attraction mode. Definitely a benefit to having some adjustment power I think.

I keep reading that there is no sweet spot in attraction mode, but then see people using variable resistors when running in attraction mode, What gives?