Tuning/Running Problems

[KarlSchmaltz]

Hi Everyone.

I have recently finished building this motor, but I am having problems tuning it, and just making it run stably.



The coil is 5-filar, all 18 AWG wire, litzed, wound to 1.2 Ohms, and R60 welding rods for the core. I have 4 superpole ferrite magnets on the rotor. All 4 MJL21194 transistors are matched, as are the 1N5408 diodes. The free spin time is relatively low, but I think that's because I'm not able to spin it very fast by hand and it doesn't have the size of a bike wheel or something big like that.

I started with a base resistance of 100 Ohms, but it wouldn't run at that (although I could see some spikes on the scope). So I lowered the base to around 60 Ohms, and it was barely able to sustain itself. I then lowered it again to around 40 Ohms, and it runs, but at a very low speed. I lowered it even more to 22 Ohms but it still runs at a very low speed and draws too much current, around 2 Amps.

I am skeptical to lower it even more. I don't know if I am doing something wrong or if superpole set-ups run on very low resistance. I wanted to ask you guys before I blow up the circuit.

Thanks,

- Karl

[citfta]

Hi Karl,

Looking at the pictures it looks like there are some problems with your soldering connections. I can see at least 2 and maybe 3 places that appear to be shorted out to one another. I don't know how to say this in a nicer way but you really need to practice your soldering until you can make nice neat connections. On the other hand your coil looks very well done. So you have the mechanical side in good shape you just need to get the hang of soldering and I think your problems will go away. The areas I saw in your picture were the 2 diodes on the right hand side seem to be touching one another and the next 2 to the left also look to be very close to touching. Also on the left side there appears to be a solder blob bridging across from one copper strip to the other. That one is just under the last large diode on the left. Thanks for posting the pictures as it makes it much easier to try and help. Get it all cleaned up and let us know how it works then.

Respectfully,
Carroll

[hobbyrobotik]

Hi Karl,

what about insulation of the transistors to the alum plate? check if your collectors are shortet. my system is very similar (same coil data)
but i use 100 ohms base resistors and trigger is 47 ohms/1W.

Dieter
(btw. do you speak german?)

[KarlSchmaltz]

Hi Karl,

Looking at the pictures it looks like there are some problems with your soldering connections. I can see at least 2 and maybe 3 places that appear to be shorted out to one another. I don't know how to say this in a nicer way but you really need to practice your soldering until you can make nice neat connections. On the other hand your coil looks very well done. So you have the mechanical side in good shape you just need to get the hang of soldering and I think your problems will go away. The areas I saw in your picture were the 2 diodes on the right hand side seem to be touching one another and the next 2 to the left also look to be very close to touching. Also on the left side there appears to be a solder blob bridging across from one copper strip to the other. That one is just under the last large diode on the left. Thanks for posting the pictures as it makes it much easier to try and help. Get it all cleaned up and let us know how it works then.

Respectfully,
Carroll

Thanks for your response and honesty Carroll. I am currently rebuilding the circuit and trying to make it more spread out and organized so nothing will short out.

- Karl

Hi Karl,

what about insulation of the transistors to the alum plate? check if your collectors are shortet. my system is very similar (same coil data)
but i use 100 ohms base resistors and trigger is 47 ohms/1W.

Dieter
(btw. do you speak german?)

Hi Dieter.

I just checked, and the collectors are indeed shorting out. I would have never suspected that to be the problem. What should I use for insulation on the transistors so they don't short out?

I do not speak much German, although I wish I could, I have been trying to learn for quite some time.

Thanks,

- Karl

[hobbyrobotik]

Hi Karl,

i just asked about the language cause it's often difficult for me to explain something in english, without beeing missuderstood.
OK, what you need for your transistor assemly is a thermal insulater as described in the beginners handbook (reading highly recommended)
the Mouser part #739-A15038003. But I use never any of them because the transistors need no heatsink. It is just a precaution for
beginners if they have faulty wiring in the circuit,which can cause overheating the device. Normally you have no problems to leave the transistors
"open air". It is more dangerous to them to leave the radiant output line open while operating. I killed a lot of them in the past this way
and i am sure i did not kill my last one :-)

have fun

Dieter

[KarlSchmaltz]

I have rebuilt the circuit, so hopefully now there is no chance of something shorting out. I also temporarily put a piece of paper between the heat sink and the transistors so the collectors don't short out.



During the rebuild I raised the base resistors from 22 Ohms to around 60 Ohms with hopes of it acting normal now, but it seems to be acting the same. I can spin it up and it will draw and 1.5 Amps but it will slowly die down and stop. It cannot sustain itself.

Am I doing something else wrong? Or should I lower the resistance back down to 22 Ohms and run at that?

Here is a video of it (scope shot included):

[Tom C]

I have rebuilt the circuit, so hopefully now there is no chance of something shorting out. I also temporarily put a piece of paper between the heat sink and the transistors so the collectors don't short out.

[ATTACH=CONFIG]1627[/ATTACH] [ATTACH=CONFIG]1628[/ATTACH]

During the rebuild I raised the base resistors from 22 Ohms to around 60 Ohms with hopes of it acting normal now, but it seems to be acting the same. I can spin it up and it will draw and 1.5 Amps but it will slowly die down and stop. It cannot sustain itself.

Am I doing something else wrong? Or should I lower the resistance back down to 22 Ohms and run at that?

Here is a video of it (scope shot included):

scalar norths are hard to get to trigger if you have big wire, what is the gauge. my scalar north rotor will only trigger with 22 on the base and 10 on the final resistor, 18 gauge wire, 18 gauge trigger. keep dropping base resistnce till it will fire, or change out your magnets to north out not scalar.

Tom C

[KarlSchmaltz]

scalar norths are hard to get to trigger if you have big wire, what is the gauge. my scalar north rotor will only trigger with 22 on the base and 10 on the final resistor, 18 gauge wire, 18 gauge trigger. keep dropping base resistnce till it will fire, or change out your magnets to north out not scalar.

Tom C

My coil is all 18 gauge. I've lowered the base resistance to 10 Ohms now and it is still not sustaining. It starts pulling over 3 Amps now and eventually dies. Are you pretty sure this is a superpole problem? If so I'll replace the magnets to their normal state.

[KarlSchmaltz]

Disregard my last post. I don't know what I did, but it is now running.

[Ed_Morbus]

Karl have you found out where the problem appeared.

Thanks.

[Catrinisin]

Hey Karl,

Whenever I have seen this behavior, it is due to the fact that the magnets are not triggering the coil with enough magnetic flux. Try moving the coil as close to the rotor as you possibly can. If that doesn't help, you may need stronger magnets or a different magnet configuration. Perhaps 4 in each spot instead of two. Still smashing north to north in the middle for the scalar super-pole effect, but having two magnets on each side of that instead of one. Not sure if your rotor is big enough for double the magnet size though I.E. Magnets: Instead of: 'SN'NS' you would have 'SN'SN'NS'NS'. If it turns out that there is not enough room on the rotor, just stack them normally and face north out.

The reason you need so much current to run is because the magnet/coil interaction is too low. It's taking a really large magnetic field inductance to interact with the magnets on your wheel. As far as the base resistance, it is taking a really low resistance to run for the same reason; The magnets are not triggering the coil with enough force.

Finally, winding the coil with smaller wire will also help get it running. This probably isn't what you want to do but I have seen this behavior start occurring in an existing working energizer when changing out only the coil for one with larger wire.

Hope this helps,
Chris

[Tom C]

Disregard my last post. I don't know what I did, but it is now running.

take out the super poles go to standard north. build a bike wheel you will see a big difference.

Tom C