Lockridge Device - Peter Lindemann

[rosehillworks]

Peter. Thank you for your explanation! I think I understand what you are saying. I hope I have this right. If we pulse the rotor winding with a much more intense voltage and amps then what the stator flux can induce as back EMF that is when we will hopefully see the large recovery spikes, and good motor power.
Thank you for the reminder, and warning about what these spikes can do to an unprotected commutator.





William

[Peter Lindemann]

Confirmation

I have confirmed it. The diodes on the positive recovery terminal prevents the recovery brushes from acting like a conventional generator when shorted together. It only let's out the spikes and doesn't slow down the motor. The weird thing is that it let's out both the positive and negative spikes according to my oscilloscope. Shouldn't the diodes only let out the positive spikes. Maybe my diode can't handle the high voltage spikes, only the low voltage generator pulses. Or maybe my diode is too slow to handle sudden discharge.

It doesn't charge a 4.7mfd, 63V cap very fast. Maybe 1 mV per second.

Brian

Brian,

Thanks for checking that out. The voltage spikes are very fast and most diodes can't catch the front lip of the event. But it is the currents that cause the drag, so they can deal with that OK. At this point, the reason the cap doesn't charge much is that we are still playing around at the bottom of the input intensity that I have imagined for these motors. The output pulse is dependent on the "change of magnetic flux" in the rotor winding. If most of that flux is produced by the stator magnet, it isn't going to change much to give us an output above the "generated voltage".

Remember, my stated plan is, once the machine is wired correctly, to run it on a voltage that is 3 times its originally designed voltage. When that is supplied from an "unlimited current source" like a battery, the rotor windings are going to be able to really TWIST the magnetic flux in the rotor caused by the stator magnets. THEN we will see the torque burst and (hopefully) the recovery pulse rise sharply.

Brian, since you are running your set-up on a limited current source, you won't see some of these effects.

I think it is a good idea to run the motors on low currents until we know they are wired correctly and all structures are in place, but that is only "Step One" in getting a motor to operate in this higher efficiency window.

Peter

[n84dafun]

Diode prevents bogging down of motor

I have confirmed it. The diodes on the positive recovery terminal prevents the recovery brushes from acting like a conventional generator when shorted together. It only let's out the spikes and doesn't slow down the motor. The weird thing is that it let's out both the positive and negative spikes according to my oscilloscope. Shouldn't the diodes only let out the positive spikes. Maybe my diode can't handle the high voltage spikes, only the low voltage generator pulses. Or maybe my diode is too slow to handle sudden discharge.

It doesn't charge a 4.7mfd, 63V cap very fast. Maybe 1 mV per second.

Brian

[Peter Lindemann]

Drag from Shorted Recovery Brushes

Brian,

I've been thinking about why your system demonstrates drag when your recovery brushes are shorted. I think it is related to the fact that you don't have the diode in the circuit yet. In that case, it can act as a generator winding and produce reverse motoring. With the diode in place, it blocks reverse currents and only lets forward currents flow when the rotor coil discharges. I believe that with the diode in place, the drag should be reduced by quite a bit.

At least, that is what I think is going on. Good luck with your experiments.

Peter

[n84dafun]

Lockridge animation

Here's an interesting video:

YouTube - OTG- Lockridge animation 2 - DMR10.wmv

The commutator segments there are huge!!! compared to my tiny commutator on my motor. If I start with a new 16 pole motor I might have to connect several segments together like that.

Brian

[n84dafun]

Brian,

Thanks for showing your pictures. The rotor wound with the Zig-Zag winding looks GREAT. All of the problems you are seeing are related to your brush arrangement. When you switch over to the one I have recommended in Post #306, and connect your rotor wires to commutator segments 180* away from each other, the motor should behave differently.

After that, we can look at what your recovery brushes are connected to, and a voltage source that can deliver more current.

Peter

The zig-zag winding is so much easier to wind compared to what I was going to do, so thanks for pointing me to that direction.

I will play around with my current brush arrangement some more because I think there's still some potential with this arrangement (and plus I'm too lazy to reconfigure it all over again, I'd rather start with a fresh 16 pole motor. )

I was thinking of using my 10 amp battery charger for my voltage source connected to my 12V deep cycle battery. The thing is, it's not 24V like the recommended power for this motor.

Brian

[n84dafun]

I would think there shouldn't be any disruption in motor function when the recovery brushes are shorted. It should be a completely separate system from the motor. If it's operating like a generator at the point of discharge where when you short the leads it goes into full load opposing the rotation... maybe the diode should be reversed?

I didn't use a diode yet, so I'll try the diode tonight, maybe that will prevent the motor from bogging down so much.

Brian

[Matthew Jones]

Well its good to hear your working through it. Keep it up.

Cheers
Matt

[n84dafun]

It may be that your generating to some extent. Pulling a load off of a generator will slow you down.
With the Zig Zag pattern your on time very well might not clear the coil from the magnet. Follow Me.
The solution may be to use 2 commutator blocks for the power cycle. That will throw the coil out of the magnets range before you start recovering.

Then again you may just want to setup a recover for higher voltage and run that thing with a higher amount of voltage. But you had better recover into batteries, those little caps fill up too fast.

Nice work though, I happy to see the motor worked out.

Matt

Matt,

I thought about using two commutator blocks, but my brushes are too close together for that, so I just added extra contacts 180 degrees away. That did the trick and helped to get things spinning even at 3.7V. As I mentioned earlier the duty cycle for one segment is too short, and adding the extra contact segment worked for me. Maybe later I can reconfigure the brushes the way Peter recommended, then I can use two adjacent contacts, which would mean the distance between the power and recovery brushes would also be two contacts away.

The caps was just a test to see how high the voltage is in the recovery terminals. Since I didn't use diodes, it only stored 11V, which is misleading because the spikes on the scope were way over pos 50V and neg 50V, which averages to 0V.

Brian

[Matthew Jones]

@Matt
When you said you had a wire shorting out on your rotor I'm wondering if its acually the commutator case or prongs shorting out on the cover. Unless you ground down the 2 studs on the cover under the new commutator locations.

Mark

I just insulated them with a peice of rubber tape. I had just enough room. You could grind them a bit but I would leave the bolt hole intact.

I had continuity between the commutator and the steel in the rotor. I know where the winding failed.

I have been doing this stuff along time, and with that experience I have been able to not only predict and avoid some problems, but I can for sure diagnose and solve my problems. I am pretty independently minded technician.

Matt

[Peter Lindemann]

The Fun of Modifying Something

Well I've run into another problem. My commutators are a little longer than the ones Matt is using and after installing them onto the board they hit on bolt studs. So I'll either have to grind down 2 spots in the cover where the bolts screw in or grind 2 spots into the commutator board and turn it about 45 degrees. Or I could relocate all 4 commutators. The other thing with my particular motor is that my brushes are wider than 1 commutator section, not a big deal but not ideal. I think my best option will be to grind down the bolt hole mounts on the cover and just use 2 bolts.

@Matt

When you said you had a wire shorting out on your rotor I'm wondering if its acually the commutator case or prongs shorting out on the cover. Unless you ground down the 2 studs on the cover under the new commutator locations.

Mark

Mark,

My recommendation is to make the modification that is the easiest, namely grinding two large flats on the cover mount studs in question to give you more clearance for your brush holders. If you grind them from the inside toward the outside, you can probably gain up to an eighth of an inch clearance without losing the functionality of the mount stud. If you simply grind it down, you can get rid of it all together and then just use two mounting bolts to hold it together. Either way, you would not have to change anything else on the rotor to make this work.

From the pictures that Brian posted, it looks like your brushes are about TWO commutator sections wide. That is no problem for now. The spacing between brushes remains the same, at ONE commutator section width.

Just solve each problem as it arises. You are almost there.

Peter

[n84dafun]

Well I've run into another problem. My commutators are a little longer than the ones Matt is using and after installing them onto the board they hit on bolt studs. So I'll either have to grind down 2 spots in the cover where the bolts screw in or grind 2 spots into the commutator board and turn it about 45 degrees. Or I could relocate all 4 commutators. The other thing with my particular motor is that my brushes are wider than 1 commutator section, not a big deal but not ideal. I think my best option will be to grind down the bolt hole mounts on the cover and just use 2 bolts.

Mark

Mark,

That's exactly what I had to do to fit my recovery brushes...grind out two bolt holes. It's also a good idea to put electrical tape on the bottom of the board and at the ends of the brush housings.

Brian

[n84dafun]

Brian, In your last video you posted it appears that you forgot to check for conduction between the second (white)power winding and your (black) recovery winding.So could you just confirm that for us so as we can be assured that this wasn't overlooked.Thx


-Gary

Gary, I tried all possible combinations of hookup and it is as expected. No conduction netween any recovery and power brushes. I think Matt and Mark are correct that the slowdown is expected and normal because of the generator effect you get when you pass a shorted coil through a magnetic field, which is what is happening when the recovery brushes touches the commutator and you short the recovery leads. This is normal. What's different is you also get the energy from the collapsing magnetic field due to pulsing the coil.

One thing I didn't do yet is put a diode om the recovery side. That's why I only get about 11V. Looking at the scope, I think I was getting 100v pos and neg spikes (at x10 mode on the probe). You can't get that from regular generator action I don't think.

By the way Mark, I had to add another set of contact points for the brushes on the commutator because the duty cycle for one segment of a twenty commutator rotor is too short. It would stop 3/4 of the way and stop. For my setup, I just connected one segment 180 degrees from the connected commutator segment of the pos brush and did the same for the neg brush. So there's 4 contact points all together.

Brian

[Mark]

Well I've run into another problem. My commutators are a little longer than the ones Matt is using and after installing them onto the board they hit on bolt studs. So I'll either have to grind down 2 spots in the cover where the bolts screw in or grind 2 spots into the commutator board and turn it about 45 degrees. Or I could relocate all 4 commutators. The other thing with my particular motor is that my brushes are wider than 1 commutator section, not a big deal but not ideal. I think my best option will be to grind down the bolt hole mounts on the cover and just use 2 bolts.

@Matt

When you said you had a wire shorting out on your rotor I'm wondering if its acually the commutator case or prongs shorting out on the cover. Unless you ground down the 2 studs on the cover under the new commutator locations.

Mark

[Peter Lindemann]

Back EMF

@ Brian
I have done the same continuity tests as you with the multimeter and got the same expected results.
I shorted the recovery wires but my motor doesn't slow down.
With 12v input i get approx 6v recovery into a 4700uf 40v cap but i had to put the recovery diode on the brush after the positive input rather than the recovery brush after the negative as in Peters drawing.

My Motor is a 2 pole with only 1 coil, i don't know if this makes a difference?

Great videos

Pat

Pat,

Your recovery voltage is lower because you are seeing the "THE TRUTH" of the "effective voltage" on the winding. As you know from my DVD,
the Effective Voltage = the Applied Voltage - the Back EMF.

Observe carefully what your machine is doing. Even write down the behaviors, especially the ones you don't understand, and correlate them with the schematic drawing of the motor that produces those behaviors. Keep good notes of your experiments. This is the only way to learn.

Also, you are correct, shorting the recovery brushes should not slow the motor down, but always have then connected to "something" to prevent arching at the commutator.

Keep up the great work.

Peter