Electric Motor Secrets

[uusedman]

@Jetis

My reed switch keep on blowing, I am going to try to trigger the attraction through a bedini style circuit. You think it is a good idea to excite the base of the transistor through inductor magnet spining?

[Jetijs]

Chris,
round corners help a lot. First I wrapped the acrylic core with several layers of non stick baking paper, the one that is used for baking cookies. Then two layers of electric tape. I put some plastic tape also to the walls of the support end plates. This works well. After the epoxy is cured, the coil pulls of with a light push and the electric tape that sticks to the coil comes off easily.
Hope this helps.

[LowTechIsCool]

prewound coils

Hi

I was hoping someone could give me advice on prewound coils. I made a polycarbonate jig, similar to Jetijs's. I am having trouble getting the coils off. On my first setup I used Teflon tape between the coil and the jig. The epoxy managed to get through some cracks and made it difficult to get off. Second I used a silicon spray, but i didnt use the teflon tape. I still got some of the epoxy bonding with the jig.

Would rounded corners on the jig help? I was thinking of using some kind of thin cardboard that I can use silicon spray on and put that in between the coil and the jig.

With Gratitude,
Chris Corkum

[uusedman]

I am dumping the inductive collapse into a 12V car battery. The source is a normal power source with a 50V 6Am max.

Hi Uusedman,

When you say "collecting the back EMF" how are you doing the load part exactly? Are you just connecting a light bulb after the diode?

It has many advantages to collect that Back emf (fly back or inductive collapse really) into a low impedance source like a cap or battery and connect your load on that. Not straight to the back emf recovery diode. It tends to often be a too high resistance for the fast spike to dump into. And can cause because of that rpm drops. (And amp draw increases)

In my view one wants to collect that flyback as quick as possible, meaning it must be able to dissipate itself fast into a load/cap/battery. You want the core in each cycle to also have time to 'relax' and reset itself to a more neutral polarity condition before the next pulse happens. You want to do it all in one cycle: Pulse the core with for example 33%duty, then somehow collect all the flyback in 33% duty and in the final 33% duty time you want the core to do nothing and relax back to a zero magnetic state as much as possible. If the core is not relaxed/reseted and still has like a 75% remanent magnetic field from the last attraction cycle you will have very little real field change and because of that bad performance. So it is important that you dump the flyback in a low resistance load, so a cap would be best. Your bulb can be connected to the cap. Hell even better would be having a circuit that dumps the cap to the laod inbetween each dc pulse.



Regards,
Steven

[nali2001]

Hi Uusedman,

When you say "collecting the back EMF" how are you doing the load part exactly? Are you just connecting a light bulb after the diode?

It has many advantages to collect that Back emf (fly back or inductive collapse really) into a low impedance source like a cap or battery and connect your load on that. Not straight to the back emf recovery diode. It tends to often be a too high resistance for the fast spike to dump into. And can cause because of that rpm drops. (And amp draw increases)

In my view one wants to collect that flyback as quick as possible, meaning it must be able to dissipate itself fast into a load/cap/battery. You want the core in each cycle to also have time to 'relax' and reset itself to a more neutral polarity condition before the next pulse happens. You want to do it all in one cycle: Pulse the core with for example 33%duty, then somehow collect all the flyback in 33% duty and in the final 33% duty time you want the core to do nothing and relax back to a zero magnetic state as much as possible. If the core is not relaxed/reseted and still has like a 75% remanent magnetic field from the last attraction cycle you will have very little real field change and because of that bad performance. So it is important that you dump the flyback in a low resistance load, so a cap would be best. Your bulb can be connected to the cap. Hell even better would be having a circuit that dumps the cap to the load in between each dc pulse.



Regards,
Steven

[uusedman]

@Eric

This is the circuit i used.
I will make a detailed video once I get more transistors.

First experiment,
Resistor 1 470 ohms
Resistor 2 470 ohms

Second experiment,
R 1 940
R 2 940


@Jetis

Any reason why the RPM decrease when collecting the back EMF?

[Eric]

re: burned trannies

hi uusedman!

just to let you know transistors are very easy to burn out when not used properly so make sure to buy a bunch. the mjl21194g by ON-semiconductor is a very good npn bipolar transistor for building the lindemann circuit. i have had a lot of success with this transistor. when used right, it never heats up in my curcuits. next it helps when ever you post a question regaurding the circuit you are working on it helps to post a drawing or reference link to a previous circuit in a past post. try to be specific in the drawing with regaurds to how you hooked each component up I.E. polarity of the pathways whether its an NPN or a PNP trans. and how you hooked up the collector, emitter, and base. chances are, if you are blowing the trans. that quickly, its hooked up in a way its not supposed to be.

hope that helps!
Eric

@Jetis

I had 2 new 3055 transistor from my bedini motor project. And, both burned Here is how:

I start the motor with the new circuit you provide and it was running well. So I i wanted to see the motor run under the condition of NOT collecting the back EMF, the motor got a little heavy RPM increase to about 510. Then, when i close the circuit to collect the back EMF while the motor is running, the transistor gets burned. Also, the transistor was getting really hot, is that normal?


The first transistor was burned having 470 ohms on base and 470 on to emitter. Second transistor was burned with 940 ohms on base and 940 on to emitter.

The motor did look running smother while collecting back EMF however, the RPM did decrease about 10%. Maybe in order to get the rotary attraction moving, it should be above a certain RPM (which is to be announced).

I am still using the previous inductors of 22 gauge, first inductor being 110 windings and second being 135 windings. Going to use 16 gauge on the next experiment, once i get more or better transistors.

@Lightly

I used 5407 diodes, is that too big?

@theremart

thanks for sharing that info

[uusedman]

@Jetis

I had 2 new 3055 transistor from my bedini motor project. And, both burned Here is how:

I start the motor with the new circuit you provide and it was running well. So I i wanted to see the motor run under the condition of NOT collecting the back EMF, the motor got a little heavy RPM increase to about 510. Then, when i close the circuit to collect the back EMF while the motor is running, the transistor gets burned. Also, the transistor was getting really hot, is that normal?


The first transistor was burned having 470 ohms on base and 470 on to emitter. Second transistor was burned with 940 ohms on base and 940 on to emitter.

The motor did look running smother while collecting back EMF however, the RPM did decrease about 10%. Maybe in order to get the rotary attraction moving, it should be above a certain RPM (which is to be announced).

I am still using the previous inductors of 22 gauge, first inductor being 110 windings and second being 135 windings. Going to use 16 gauge on the next experiment, once i get more or better transistors.

@Lightly

I used 5407 diodes, is that too big?

@theremart

thanks for sharing that info

[uusedman]

@Jetis

I had 2 new 3055 transistor from my bedini motor project. And, both burned Here is how:

I start the motor with the new circuit you provide and it was running well. So I i wanted to see the motor run under the condition of NOT collecting the back EMF, the motor got a little heavy RPM increase to about 510. Then, when i close the circuit to collect the back EMF while the motor is running, the transistor gets burned. Also, the transistor was getting really hot, is that normal?


The first transistor was burned having 470 ohms on base and 470 on to emitter. Second transistor was burned with 940 ohms on base and 940 on to emitter.

The motor did look running smother while collecting back EMF however, the RPM did decrease about 10%. Maybe in order to get the rotary attraction moving, it should be above a certain RPM (which is to be announced).

I am still using the previous inductors of 22 gauge, first inductor being 110 windings and second being 135 windings. Going to use 16 gauge on the next experiment, once i get more or better transistors.

[theremart]

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[uusedman]

@uusedman

You cannot connect diodes in parallel. I already explained why in my posts to Jetijs.

I glanced over it, tonight, I will try a big diode.

[lighty]

@uusedman

You cannot connect diodes in parallel. I already explained why in my posts to Jetijs.

[Jetijs]

uusedman, try this circuit:



Your reedswitch will eventually burn out if much current is going through it. Using the circuit above, the reedswitch will only need to switch small current just to turn the transistor ON. and the rest of the current will flow through the transistor.You can use 2n3055 transistor for this, they are cheap. As for the resistors, try different values (both the same) from 1k down to 200 Ohms.
This should improve things a lot

[uusedman]

I cant believe it took me this long to answer.
Let me know what you think. The switch is a magnetic reed switch, 50v 2amp.

[lighty]

Eric's recommendations are all correct. One can surely engineer more sophisticated circuitry. I do it for living and I wrote that if I was engineering similar stuff for me or other professionals I would surely employ much more complex circuits. However if something goes wrong in more complex circuit then you need more knowledge and experience in order to troubleshoot it. Jetijs is not EE professional and he has to rely on myself or Eric to troubleshoot it on the distance. And it is a major obstacle. Also, Jetijs is living in a location where getting even some basic components is a kind of obstacle for him.

Circuit driver stage at the moment works just fine as can be seen by the gate signal. So, at the moment no additional Schmitt triggers are needed. It's basically a disagreement in apporach between I and Eric on a purely professional level. In my view when something works just fine there is no need to make it more complex because you can only introduce more variables that can cause something to go wrong. And as I already stated, the more complex circuit is, the harder troubleshooting is.

If MOSFETs are only slightly warm to touch (and I understand that is so by Jetijs's description) there is nothing wrong with circuit or driving. The only thing he can do is to try to lower the ON resistance. He can do it by employing better MOSFETs with lower ON Rds or by paralleling several MOSFETs. If paralleling MOSFETs additional problems might occur so for the sake of simplicity I would chose the other way. Eric's suggestion for MOSFET with much lower ON Rds is sound. I would of course suggest something that is more accessible to Jetijs but the basic idea is the same.

The only thing getting hot in Jetijs setup is isolation diode and I already explained what he has to do in order to resolve that obstacle. There is a point of the current levels going through that diode but don't forget that there is a large buffer capacitor basically providing energy to the coils so probably a slower (and larger) diode could be used at that position in circuit.


All being said, Eric gave some good advices but I think it won't help the situation for the reasons I already stated. It could, however complicate things to a level where possible troubleshooting will be harder. I worked in ariforce for a number of years and I worked both on complex sophisticated electronics in US helicopters and on more simpler and more rugged electronics in Russian helicopters. Guess which one failed less often and which one was easier to troubleshoot and repair?