chaging gears-sweet spot?

[matt b]

hi all...
was hoping to get a better idea on what is happening when the machine appears to change gears?
(sorry this is the best description i can think of)

when the machine starts up and the rpms are climbing it will get to a certain rpm and the voltage(output?) suddenly drops... what causes this?

is this related to the sweet spot?

depending on the setup... eg number of coils, if they are connect to one or multiple trransistors... this will affect the amount of times it appears to do this

appreaciate any thoughts on this =)

[Ren]

Hi Matt,

I definitely know what you mean, Ive used that analogy before, its just like changing gears in a car, input amperage drops, and wheel speeds up. Ive seen it on nearly all my builds, sometimes the resistance can be tweaked again once up to speed to get another gear so to speak. Perhaps it has to do with pulses per pass?

BTW nice to see someone posting here who lives nearby. Im on the central coast, I work at Wahroonga.

Interested also to see what others think, q1 - q8 comes to mind as well.



Regards

[greghaa]

From my understanding that is the sweet spot and a wheel often times will have a few of them.
When tuning, and looking for fastest speed with lowest draw, that will often be where that gear
change is, on the high end. If that makes any sense.

Hope this helps.

[Marcia Stockton]

The "changing gears" phenomenon is simply the transition between a given number of pulses per magnet to the next higher or lower number. If you are tuning with a scope you can clearly see this. Once the machine is operating with a certain number of pulses per magnet, you can vary the current for a while without causing an increase in the number of pulses per magnet. Then suddenly you pass a current threshhold and the rotor is going a little faster and so the dwell time when a magnet is near the coil is shorter, and there is not time for as many pulses as before.

Marcia

[matt b]

Hi and thank you for your replys =)

Ah that makes a lot more sense now, would explain the sudden drop in output going from say 3 pulses per magnet to maybe one pulse per magnet with only a small increase in the rpm

so what would be more desirable- more pulses per magnet at lower rpm or higher rpm but less pulses per magnet?

Thanks in advance
Matt b

[Ren]

This is something that may change from build to build. Generally 1 pulse per pass gives the fastest speed in my experience, but it may not always equate to the best charging. A simple way to view your pulses per pass if you dont have a scope can be seen here. You can see how it affects the speed of the rotor as pulses per pass are increased.

Regards

Hi and thank you for your replys =)

Ah that makes a lot more sense now, would explain the sudden drop in output going from say 3 pulses per magnet to maybe one pulse per magnet with only a small increase in the rpm

so what would be more desirable- more pulses per magnet at lower rpm or higher rpm but less pulses per magnet?

Thanks in advance
Matt b

[Kasper Westeraa]

Tuning for the sweet-spot keeps puzzling me...

@ greghaa: "on the high end". Do you mean, that when you decrease resistance, and the amp draw goes up - then suddenly falls and climbs again to the level from where it dropped - is the high end of that "gear" i.e. the sweetspot? My SSG has two of them, and I used the one "on the high end" of the biggest amp draw level for my 20 runs. But as mentioned earlier, this subject keep puzzling me.

Please feel free to comment anyone! I can't let it go...

Kasper.

[Huey]

Sweetspot

hi all...
was hoping to get a better idea on what is happening when the machine appears to change gears?
(sorry this is the best description i can think of)

when the machine starts up and the rpms are climbing it will get to a certain rpm and the voltage(output?) suddenly drops... what causes this?

is this related to the sweet spot?

depending on the setup... eg number of coils, if they are connect to one or multiple trransistors... this will affect the amount of times it appears to do this

appreaciate any thoughts on this =)

Hello, And I know on all my setups the fastest rpm is not the goal. Its when I tune mine to that spot where output is highest, usually at low rpm and highest resistance or near highest on my pots. Most of the time I let them spin up fast then back them down to the highest output. I have 1 setup I call the screaming cricket its so darn loud at the sweetspot. Still learning but not tyred of building yet. Huey

[greghaa]

Tuning for the sweet-spot keeps puzzling me...

@ greghaa: "on the high end". Do you mean, that when you decrease resistance, and the amp draw goes up - then suddenly falls and climbs again to the level from where it dropped - is the high end of that "gear" i.e. the sweetspot? My SSG has two of them, and I used the one "on the high end" of the biggest amp draw level for my 20 runs. But as mentioned earlier, this subject keep puzzling me.

Please feel free to comment anyone! I can't let it go...

Kasper.

Yes, there were points that the draw would drop and the wheel would maybe speed up a bit and it would seem more smooth or something. John K. put me on to the timing light and
that helped me see what was going on. I started with high resistance and would go through at about 10 ohm increments documenting draw, resistance and RPM's. This allowed me
to map out the whole wheel in terms of what it would draw and where sweet spots were. Then I could make a determination of what is best for charging. Hope this helps...

[Branch Gordon]

I've been working on trying to tune the 3PM kit (which may be a pointless endeavor considering all that is wrong with it).

I start with no resistance on the pot. As I raise the resistance to around 100 ohms, the wheel speeds up to it's fastest RPM. This spot however fails the 1 ohm resistor test (too hot) As I increase the ohms from there, the primary draw decreases as do the RPMS. There is a spot around 3600 RPMs where the current draw jumps up a bit instead of continuing the decrease. Is that the sweet spot? Should I adjust the resistance to just before the jump, or right on it?

[John_Koorn]

Hi Branch,

When tuning start from a high resistance and gradually lower it until you get the fastest rpm.


John K.

[Branch Gordon]

Hi John-

I am sorry that is what I meant. I am starting at the the highest resistance on the pot (it's a 1k pot), and moving it slowly down.

Hi Branch,

When tuning start from a high resistance and gradually lower it until you get the fastest rpm.


John K.

[Howard Wetsman]

I had always heard the explanation that Marcia gave, pulses per magnet, and watching on the scope that was in deed correct. Yesterday however I did something that makes me question the "per magnet" part. I have tried to replicate Patricks SS SSG w CPD mod. I built a matched component 7 circuit board. I used an r-charge 8 filar #23 coil. I put a 1K pot between the 1M pot and the board to act as the "branch resistor". As the 1M pot lowers in resistance the frequency of firing increases and with the 1K pot set at 1K, I get a triple pulse. As I lower the 1K pot I can tune it to one pulse per firing. This is the same resistor in the same place in the circuit I used to tune the rotor SSG to one pulse per magnet, BUT THERE ARE NO MAGNETS. Maybe there's something fundamental and easy to understand here that I don't understand, but I thought it had to do with the amount of time the magnet was over the core, but it can't be that in my set up. Any thoughts?
h

[Tom C]

I had always heard the explanation that Marcia gave, pulses per magnet, and watching on the scope that was in deed correct. Yesterday however I did something that makes me question the "per magnet" part. I have tried to replicate Patricks SS SSG w CPD mod. I built a matched component 7 circuit board. I used an r-charge 8 filar #23 coil. I put a 1K pot between the 1M pot and the board to act as the "branch resistor". As the 1M pot lowers in resistance the frequency of firing increases and with the 1K pot set at 1K, I get a triple pulse. As I lower the 1K pot I can tune it to one pulse per firing. This is the same resistor in the same place in the circuit I used to tune the rotor SSG to one pulse per magnet, BUT THERE ARE NO MAGNETS. Maybe there's something fundamental and easy to understand here that I don't understand, but I thought it had to do with the amount of time the magnet was over the core, but it can't be that in my set up. Any thoughts?
h

Howard,

with the rotored SG you are dealing with mechanical switching, at some point in time the wheel will not spin any faster for the amount of current flowing thru the coil. with a solid state circuit (scalar charger) you can get switching in the Khz region if you want, no magnets are needed. you can switch a rotored SG with halls, opto's and a timing disc variable resistance in a trigger circuit. the solid states can be done with a 555 timer, the wind circuit, the CPD mod, using a function generator, probably a few others I have not even seen yet

Tom C