Electric Motor Secrets

[Jetijs]

Hi everybody.
Today I went to a bearing shop and bought the best bearings they had for my purpose. I replaced the bearings and started the motor. If with previous bearings I could reach speeds up to 538 RPM at 0,55 A current draw, then with these bearings I could get up to 1376 RPM at only 0,31A current draw The first time I was afraid that the whole thing will fly away
Here are my results now with the new bearings:
One transistor Current draw - 0,30A Speed - 1335 RPM Voltage 24V
Two transistors Current draw - 0,31A Speed - 1363 RPM Voltage 24V
Three transistors Current draw - 0,31A Speed - 1376 RPM Voltage 24V

The speed increases over a period of 1 minute or so till it reaches the maximum. Also the current draw decreases slowly in this time, till it reaches the minimum draw. It seems that the faster the rotor turns, the less current it draws. Also I noticed another cause of inefficiency - the screws on my rotor also retain some magnetism, I should change them. I will make a video tomorrow and upload it on youtube
Thanks for now
Jetijs

[mrl]

Gone dead

Whatever happened to the project? No one seems to be posting very much.

Has the project gone dead?

[sykavy]

just started my first steps

I just wound my coil to start my Lindemann motor experiment. It is going to be easier for me to do the piston set-up you diagramed on your DVD. I hope this is allowed. I have finished my coil today and hope to finish the rest soon but I am very busy and very slow.
I was thinking of doing the piston set-up before Elis posted his comments. His solinoid is different from the DVD drawings. Plus from what I can understand they both work on the same basic atraction principale only the geometry is changed (which could effect strength but I don't know plus that isn't important to me now all I want to do is get something started). I'll hopefully move on to the rotary one later.
Keep your fingers crossed that I don't get distracted.

[Aaron]

thread topic?

Hi Elias,

Please post a response to me here of a subject of a new thread to move your posts over to and I'll do that for you and then I'll delete the posts in this thread.

I love your posts and they're a great contribution to this forum. We just want to keep this thread super on topic.

[Jetijs]

Peter,
I resoldered everything on a new soldering plate. I decreased tha optotrigger bridge resistance to 500 Ohm. Now I ran the motor with only one transistor at a time, to verify that each one of them has the same performance. First transistor got the RPM's up to 480. The second transistor performed the same. The third transistor was a little weaker and got the RPM's to 475.5 (4.5 RPM's less than other two). Now I connected them in parallel, here are the results:

# of transistors | Current draw |RPM's

1_______________0,55A_______480
2_______________0,55A_______527
3_______________0,55A_______538

Does this mean I need to remove some more turns from the startor coil?
Thank you,
Jetijs

[Peter Lindemann]

Off Topic

I uploaded an image to demonstrate this concept. A picture is worth a thousand words! Please tell me what you think.

Kindest Regards

Elias,

This is totally OFF TOPIC for this thread. Please delete these posts and start a new thread.

Thanks,

Peter

[Jetijs]

Ok, here is the exact circuit:

all the diodes are rated 1000V and 4A and all the resistors are 2w.

Before removing 50 turns of wire I made another test, just to be sure. This time I used digital amp meter. Here are the results:

Transistors Current Voltage RPM
1 transistor 0,44A 24V 450
2 transistor 0,44A 24V 481
3 transistor 0,45A 24V 486

And these are the results when the 50 turns were removed:

Transistors Current Voltage RPM
1 transistor 0,55A 24V 463
2 transistor 0,56A 24V 562
3 transistor 0,56A 24V 572

Just saw the information in your edited post about the reducing the resistance of the optotrigger voltage divider. I think that you are right about that one of the transistors may not open fully, because when I try to run the motor with only one transistor I see a difference in performance compared with other two ransistors. I try them all out one after another. That means one of them does not fully open.
I will try to reduce the resistance as you told and post the results then

Edit:
One of the NPN's keeps blowing. I already replaced it 3 times. It always blows when I run the motor only with that one transistor and that happens on the very first impulse. There is a flash in the neon bulb acros the collector and the emitter of that transistor and the motor stops. One time the transistor blew so that it was constantly on, drawing 1.5A from the battery, other two blew with a little click sound and just stopped responding, when I removed them, I could measure a resistance of 460 Ohms between collector and base that is not there on a new transistor. I double checked the circuit and can not see why that happens, everything seems to be exactly like in the circuit above. Also that transistor does not blow when I run the motor with all thre coil strands and all three transistors. I will resolder everything on a new plate tomorrow and try it again as it is already late today.

Thanks

[Peter Lindemann]

Two Possibilites.....

Thanks elias,
but the optical switching works excellent.
Ok, here's the summary.
I finished the circuit with optical switch. Now I can get perfect timings for all four pulses per perriod. I had problems with bearings, when I bought them, they were sealed and filled with a thick grease that would not allow the bearing to rotate by its inertia for some time. When I cleaned the grease out, the bearing would rotate for about half a minute on its own by its inertia, but it also made some noise as if the balls inside were loose. Also some backlash appeared. So I cleaned the grease out and lubricated the bearings with some synthetic oil. I mounted them on the motor and could get speeds up to 900 RPM, but the motor made a terrible noise as if the bearings were broken, so I replaced them by new ones, but that decreased the rotor speed to about 500RPM. Anyway, I soldered the circuit and started testing. At first I run the motor with only one NPN transistor and one strand of the startor coil.
I slowly increased the resistance of the 200 Ohm voltage divider to see how high I can go till the RPM's start to dropp. I went up about 100 Ohms at a time. I used two high wattage pots for this. When I reached 600Ohms, I noticed a decrease in speed of the rotor. So I reduced the resistance to 550 Ohms and got almost the same RPMs as with 200 Ohms, so I decreased the resistance just a bit less than 550 and got the RPMs I need. Now there is a voltage divider at each NPN base with the resistance of 430 Ohms.
So at first I used only one NPN transistor and one coil, I put a charging battery on the output and got 485 RPM with 0.4 A current draw at 24V. Then I run the motor with two NPN transistors and two coils in parallel as in the circuit above. This time I got exactly 500RPM and a barely noticable increase in current draw. And when I put in the third transistor, the RPM's increased to 508. That is not what I expected. I figured, maybe I need a high wattage low resistance resistor between each emmiter of the NPN's and the negative battery lead. Because the transistors are not all exactly eaqual, one may open more than others and so take all the current on itself, leaving only small current for other transistors. So with these resistors between emmiters and negative terminal I could ballance the current for each transistor eaqually. Is this right? I figured that I could make such a resistors form a resistance wire wound to a correct ommage.
Thats it for now. I will test some more. Here's a picture of the optical switching part:


Thanks,
Jetijs

Jetijs,

Everything sounds good. The three parallel voltage dividers are doing what they are supposed to do.

There are two possibilities to explain the performance. The first possibility is that the PNP device is current starved and not opening up all the way. Try some smaller resistors in the voltage divider run by the photo-transistor. Your photo-transistor can handle 50ma, so try two 500 ohm resistors in this bridge.

If that makes no difference, then the motor is telling you that the inductive rise-time of the coil already fills the ON-TIME window at about 500RPM. So, to get the motor to run faster, take 50 turns OFF the coil. Remember I said originally that you should start with your #21 wire at 250 turns, and if the need arises, that we could take some turns OFF. Well, that time may have arrived!

Start by changing the resistors in the P-T section. If that doesn't work, remove 50 turns on your coil. The motor should turn faster, draw more current, and charge the back battery faster.

Also, please draw out the entire circuit as you have it now with the battery being charged, just so I can see that there are no other mistakes.

Great work!!!

Peter

[Jetijs]

Thanks elias,
but the optical switching works excellent.
Ok, here's the summary.
I finished the circuit with optical switch. Now I can get perfect timings for all four pulses per perriod. I had problems with bearings, when I bought them, they were sealed and filled with a thick grease that would not allow the bearing to rotate by its inertia for some time. When I cleaned the grease out, the bearing would rotate for about half a minute on its own by its inertia, but it also made some noise as if the balls inside were loose. Also some backlash appeared. So I cleaned the grease out and lubricated the bearings with some synthetic oil. I mounted them on the motor and could get speeds up to 900 RPM, but the motor made a terrible noise as if the bearings were broken, so I replaced them by new ones, but that decreased the rotor speed to about 500RPM. Anyway, I soldered the circuit and started testing. At first I run the motor with only one NPN transistor and one strand of the startor coil.
I slowly increased the resistance of the 200 Ohm voltage divider to see how high I can go till the RPM's start to dropp. I went up about 100 Ohms at a time. I used two high wattage pots for this. When I reached 600Ohms, I noticed a decrease in speed of the rotor. So I reduced the resistance to 550 Ohms and got almost the same RPMs as with 200 Ohms, so I decreased the resistance just a bit less than 550 and got the RPMs I need. Now there is a voltage divider at each NPN base with the resistance of 430 Ohms.
So at first I used only one NPN transistor and one coil, I put a charging battery on the output and got 485 RPM with 0.4 A current draw at 24V. Then I run the motor with two NPN transistors and two coils in parallel as in the circuit above. This time I got exactly 500RPM and a barely noticable increase in current draw. And when I put in the third transistor, the RPM's increased to 508. That is not what I expected. I figured, maybe I need a high wattage low resistance resistor between each emmiter of the NPN's and the negative battery lead. Because the transistors are not all exactly eaqual, one may open more than others and so take all the current on itself, leaving only small current for other transistors. So with these resistors between emmiters and negative terminal I could ballance the current for each transistor eaqually. Is this right? I figured that I could make such a resistors form a resistance wire wound to a correct ommage.
Thats it for now. I will test some more. Here's a picture of the optical switching part:


Thanks,
Jetijs

[elias]

Why not use hall effect switches?

Ok, tkank's Peter
For what I understood from your post, the circuit should now look something like this:

Is that correct?
Thank you

Edit: Can I use the MJ2501 PNP transistor for triggering? It is a high power transistor, but I found some of them laying around. The max base current of this transistor is 0.2A, but that is the absolute maximum rating. Here is the data sheet:
MJ2501 pdf, MJ2501 description, MJ2501 datasheets, MJ2501 view ::: ALLDATASHEET :::
If I can use this, then I need no aditional parts and can start soldering.

Jetijs

Jetijs,

I was thinking that you would be able to use a hall effect switch instead of a reed switch without any modifications to your timing wheel. If you're interested tell me I'll post you a simple schematic for this purpose, although it is quite easy to design such a circuit. But if you've done it with optos then that's ok. Just a suggestion.

Elias

[lighty]

Thank you for the answer. You're correct, of course- extremely fast switching times can be achieved with MOSFETs but for the extreme purposes one has to use special MOSFETs, diver ICs with additional gate sink and clamp and several other things. Thinking of it again I can understand your logic in this matter.

[Peter Lindemann]

MOSFET vs Bi-Polar Transistor

Why bipolar transistors? I am not asking this because I doubt your judgment but because I really want to know. Is there any difference at this stage? I mean from first hand knowledge I know there is a significant difference when dealing with dielectricity but at this stage it's simply a switch. Or not? I never experienced any adverse effects when I compared MOSFET and BJT as switch (although the MOSFET proved to be faster and had lower turn-on resistance). Is there any difference?

Lighty,

As you know, MOSFETs can work with these circuits. The biggest problem with FETs is the capacitive nature of the gate. Getting the device to turn ON quickly is no problem, but getting them to turn OFF quickly is a little harder. The little FET driver ICs help, but that is one more level of complication. I am trying to demonstrate circuits that are simple to understand, as well as work effectively.

Again, for you, I'm sure you can make MOSFET circuits do all of these things, but I am trying to keep it simple for learning purposes.

Peter

[Peter Lindemann]

Correct...

Ok, tkank's Peter
For what I understood from your post, the circuit should now look something like this:

Is that correct?
Thank you

Edit: Can I use the MJ2501 PNP transistor for triggering? It is a high power transistor, but I found some of them laying around. The max base current of this transistor is 0.2A, but that is the absolute maximum rating. Here is the data sheet:
MJ2501 pdf, MJ2501 description, MJ2501 datasheets, MJ2501 view ::: ALLDATASHEET :::
If I can use this, then I need no aditional parts and can start soldering.

Jetijs

Jetijs,

Yes, that is the idea. Try the PNP you have on hand. Also, see if the 200 ohm resistors can be a higher value, like 680 ohms, and still turn your power NPN on all the way. Run the test with one coil and see how it works. Then try to power all three coils.

Peter

[lighty]

My suggestion is that you stay with the Bi-polar Transistors for now and go with one stage of signal amplification in between the photo-transistor and the power transistor.

Why bipolar transistors? I am not asking this because I doubt your judgment but because I really want to know. Is there any difference at this stage? I mean from first hand knowledge I know there is a significant difference when dealing with dielectricity but at this stage it's simply a switch. Or not? I never experienced any adverse effects when I compared MOSFET and BJT as switch (although the MOSFET proved to be faster and had lower turn-on resistance). Is there any difference?

[Jetijs]

Ok, tkank's Peter
For what I understood from your post, the circuit should now look something like this:

Is that correct?
Thank you

Edit: Can I use the MJ2501 PNP transistor for triggering? It is a high power transistor, but I found some of them laying around. The max base current of this transistor is 0.2A, but that is the absolute maximum rating. Here is the data sheet:
MJ2501 pdf, MJ2501 description, MJ2501 datasheets, MJ2501 view ::: ALLDATASHEET :::
If I can use this, then I need no aditional parts and can start soldering.

Jetijs