Bedini Schoolgirl

[Aaron]

Bedini School Girl Science Fair Motor discussion. This isn't for the versions that charge batteries. This is really for beginners who just want to learn more about the very simple roller skate version.

Get a copy of the only Authorized Bedini SG Handbook - Bedini SSG

[Aaron]

Bedini Schoolgirl schematic for beginners

These 2 schematics are the best ones to start with to learn the Bedini circuits. Don't worry about energy recovery and charging batteries with them. Just build this to learn the prinicples of the monopole.





I didn't even know what a transistor was when I build my first one. When you looked at the circuit, it literally looked like the schematic. You don't have to spend a lot of money either. I used a pink roller skate wheel from a $2 pair of roller skates from the Goodwill.

[sykavy]

These 2 schematics are the best ones to start with to learn the Bedini circuits. Don't worry about energy recovery and charging batteries with them. Just build this to learn the prinicples of the monopole.

I didn't even know what a transistor was when I build my first one. When you looked at the circuit, it literally looked like the schematic. You don't have to spend a lot of money either. I used a pink roller skate wheel from a $2 pair of roller skates from the Goodwill.

thanx so much I never thought id get such a great welcome. Im going to try it, so I may not be posting much until i get it working
God bless

[Aaron]

easy to do

There is an official Bedini SG manual finally available: Bedini SSG

You'll probably get it working on the first try.

Use a 10ohm resistor to start with, easier to get it running on that. Not as efficient, but just get it to work.

1 X 10ohm resistor
1 X 1N914 diode
1 X MPS8099 transistor or RCA3055 or 2N3055 either of those will work fine

Get enough wire of #23 and #26 or closest you can find for those. Enamel coated magnet wire..enough to wind about 600 turns on the coil to the dimensions in those schematics. Make sure to wind it so that when you put + top the top of the coil and - at the bottom that the magnetic field on the coil is NORTH at the TOP. Wind both of those wires together at the SAME time around the spool.

The core for the coil can be a soild piece of iron or use a bunch of smaller pieces of welding rod cut to lenght and bundled together.

The transistor has a collector, emitter and base. The collector is the input, the emitter it the output. With these NPN transistors, there is no connection through the transistor from collector to emitter. The faucet is shut off basically. To make the connection, it requires a bit of current at the base...that is what the trigger wire is for. That turns it on and when the power is no longer at the base, the transistor shuts off. It is just an off and on switch triggered by the base.

When you buy the transistor, the package will give you a diagram or you can find it online which lead is what. BCE are the 3 you need to know. Just connect the coil wires, diode and resistor to each other like in the diagrams John drew.

The resistor doesn't matter which way you put it. The diode, the little black stripe needs to be towards the base of the transistor.

Make sure the wheel spins really, really easily. One little spin and it just keeps going. You can make it like mine where the wheel spins around the shaft or you can make it fixed to the shaft so the shaft spins in some bearings in the frame uprights.

You can use regular ceramic magnets on the rotor. Just make sure North is facing out on all 4 magnets so that south are all facing towards the axle.

The little black sealed gel cell batts are good ones to play with for starters. Use 12 volt ones.

When it is all hooked up, you give a slight little spin on the wheel and it will just start speeding up as fast as it can go.

When you get it running with these parts (use the 10ohm resistor), then you can switch out the resistor to something like a 680ohm to see if it will run on that. You basically want as much resistance as possible while still letting enough get through to trigger the transistor. That is the idea anyway.

There are a LOT of people around the world who have build these Bedini machines so you won't have a problem getting people to help you out.

[sykavy]

Get enough wire of #23 and #26 or closest you can find for those. Enamel coated magnet wire..enough to wind about 600 turns on the coil to the dimensions in those schematics. .

A couple of questions what is enough wire?
and
What is Enamel coates magnetic wire? Is the wire magnetic?

That looks like three questions mea cupa

[Aaron]

magnet wire

Hi Sykavy,

The enamel coated magnet wire is copper wire with a transparent coating of enamel. It comes in different thicknesses measured in guage like 23, 26, etc... the lower the number the fatter it is. The wire isn't magnetic but when wound into a coil and power is applied, it will turn into an electromagnet. The wire is insulated with the enamel so the wire dosn't short itself.

You want enough wire to wind 600 turns of both wires at the same time. 100-200 feet of each should be enough. Just wind the coil so that it fills out to the spool ends. Follow the dimensions of the coil in John's drawings. 100-200 feet doesn't cost that much and you can get at most electronic supply places in most towns. I buy wire by weight like 10 pound spools of whatever gauge...That is a lot more than you need, but shop around.




A couple of questions what is enough wire?
and
What is Enamel coates magnetic wire? Is the wire magnetic?

[sykavy]

Hi Sykavy,

The enamel coated magnet wire is copper wire with a transparent coating of enamel. It comes in different thicknesses measured in guage like 23, 26, etc... the lower the number the fatter it is. The wire isn't magnetic but when wound into a coil and power is applied, it will turn into an electromagnet. The wire is insulated with the enamel so the wire dosn't short itself.

You want enough wire to wind 600 turns of both wires at the same time. 100-200 feet of each should be enough. Just wind the coil so that it fills out to the spool ends. Follow the dimensions of the coil in John's drawings. 100-200 feet doesn't cost that much and you can get at most electronic supply places in most towns. I buy wire by weight like 10 pound spools of whatever gauge...That is a lot more than you need, but shop around.




A couple of questions what is enough wire?
and
What is Enamel coates magnetic wire? Is the wire magnetic?

Thanks! I also don't know how to tell the north from the south on the magnets. Also when I wind the spool does it have to be a special material?

How do I know which end of the spool of wire is north? Should the winding be very tight?
PS: The first law of history is not to dare to utter falsehood; the second, not to fear to speak the truth

[Aaron]

John Bedini | Radiant Energy

John Bedini | Radiant Energy

[sykavy]

John Bedini | Radiant Energy

the radiant stuff is cool and i can understand some of it but it isnt really the basic stuff i thought this thread was about.

How do i know the difference between north and south pole on the magnet? Im not joking , i really dont know.

I made my SG according (i think) to the plans you gave me above but the coil gets very hot in a short time. Have i done something wrong?

[Aaron]

how to tell north from south

Hi Sykavy, I apologize. I forgot to answer your question about the poles.

click the thumbnail picture below.

Yes, wrap the coil pretty tight and wrap both wires together...both the trigger and power wire together.

The thumbnail picture below (click it) shows how to wrap the coil so that when you put + at the top and - at the bottom, you will get a NORTH field at the top of the coil. As long as the wire at the top is coming off the coil towards you from around the right side and the bottom wire is coming off the coil towards you from around the left side and you put + and - as shown, you will get a NORTH field at the top.

I like to start with the wires coming off the bottom of the coil poking off from the left side pointing at me. Then, I wrap upwards and down up and down up and down and I try to end at the very top...that is just to prevent confusion, you could of course end them both at the top and both at the bottom, but this makes it simple.

If you wind the coil like that you get the north field when a battery is attached to the coil. Then if you take a permanent magnet and put a fact towards the coil like this, it will repel if you are facing the north of the magnet to the coil. If you have south facing coil, it will suck to the coil when the coil is powered.

I hope this helps. Can you draw a diagram of exactly what you build and the components you used, size of wire and how many wraps, etc... did you wrap it like I described or did you wrap it backwards? You can make the whole thing work in reverse but if you are able to easily, I would unwind the coil and rewrap it properly like the diagram.

I didn't post that Bedini link for you to go figure it out yourself, I just did that to provide a link. This thread is intended for first time schoolgirl motor builders.

[sykavy]

Hi Sykavy, I apologize. I forgot to answer your question about the poles.

click the thumbnail picture below.

Yes, wrap the coil pretty tight and wrap both wires together...both the trigger and power wire together.

The thumbnail picture below (click it) shows how to wrap the coil so that when you put + at the top and - at the bottom, you will get a NORTH field at the top of the coil. As long as the wire at the top is coming off the coil towards you from around the right side and the bottom wire is coming off the coil towards you from around the left side and you put + and - as shown, you will get a NORTH field at the top.

I like to start with the wires coming off the bottom of the coil poking off from the left side pointing at me. Then, I wrap upwards and down up and down up and down and I try to end at the very top...that is just to prevent confusion, you could of course end them both at the top and both at the bottom, but this makes it simple.

If you wind the coil like that you get the north field when a battery is attached to the coil. Then if you take a permanent magnet and put a fact towards the coil like this, it will repel if you are facing the north of the magnet to the coil. If you have south facing coil, it will suck to the coil when the coil is powered.

I hope this helps. Can you draw a diagram of exactly what you build and the components you used, size of wire and how many wraps, etc... did you wrap it like I described or did you wrap it backwards? You can make the whole thing work in reverse but if you are able to easily, I would unwind the coil and rewrap it properly like the diagram.

I didn't post that Bedini link for you to go figure it out yourself, I just did that to provide a link. This thread is intended for first time schoolgirl motor builders.

Thanks, but why is the coil getting so hot? This seems to be my biggest problem. Ill try it and get back to you thanks again for the help

[Shamus]

Hi all, I'm new here so bear with me if this is all old hat.

I've been building my recreation of the schoolgirl and she's not behaving very well. I've already burned out two transistors, one by trying to solder the coil wire to the case--way too much heat!--and the other? Not sure what happened there. At any rate, trying to chase down magnet wire around here (Austin, TX area) has been difficult to say the least. Sure, you can get it at Radio Shack or Fry's, but only in ridiculously small quantities like 40 ft. (for #22) and 75 ft. (for #26). You can get a whopping 200 ft. of #30, but that's probably way too small.

So, the problem is most likely in my coil--I was only able to get 388 turns out of that 75 ft. of #26 which was wrapped bifilar with #24. In checking the coil with a voltmeter and spinning the rotor near it only around 5 mV max comes through as induced current. I'm guessing that this is not nearly enough current to bias the transistor on. When sending current through the coil, though, it generates a good kick. If I pulse current through it by hand, I can get the rotor to turn fairly well.

Anyway, a few questions come to mind about this circuit. First, I notice that there's a ground connection shown--is this strictly necessary? I saw on this page (near the bottom) that the circuit is almost identical (the only difference is the diode going to the recharge battery), but they caution that if there is no load that a neon bulb is required to keep the transistor from burning out. Is that the purpose of the ground in this circuit?

The other thing is I notice a lot of bifilar windings have the wires twisted around each other. Is that really necessary to get this to work? Perhaps the better question would be does it confer an advantage over winding the wires side by side (the way I did my coil)?

I'll post some pictures once I get this thing going. I'm almost 100% sure that the problem is that there's just not enough turns on my coil to induce enough current to bias the transistor. I've got some longer magnet wire lengths on order, so once those arrive we'll see what happens.

[Aaron]

hot transistor

Hi Shamus,

If the transistor gets hot, I'm not sure it is from to few turns on the coil.

There are two things I would double check. Are the wires wrapped in the correct direction around the coil? Is the power wire going to + on the battery coming off around the right side of the coil towards you? And is the power wire going to the collector on the transistor coming off the coil from around the left side of the coil? And are the magnets for sure North facing out? These can still run even if everything is backwards and if so, it can heat up...I've experimented with that and got a hot transistor. I know this seems so simple that it can never be backwards but sometimes it is the simplest thing.

Have you tried spinning the wheel faster to get more induction to kick it off? Ideally, it will start by barely moving the rotor. If you have a lower resistance resistor at the base like a 10ohm, it will run way easier than a 680 for example but is less efficient but if you want to at least see if it all hooked up properly, drop the resistance and try it out. Lower resistance needs less speed on the rotor to get it going.

If the coil is wrapped correctly as indicated above and you hook it to a battery, the north field should push up on the North magnet facing out on the rotor. Of course you already know this but I'd make sure these 2 things are absolutely correct.

What components are you using? Transistor, resistor, diode? You can see in my picture here of the roller skate motor that I have a 2n3055 transistor and there isn't a 90v neon bulb. You don't really need it I don't think unless you have quite a few more turns.

You can twist the power and trigger wire together before wrapping on coil for a little more efficiency. Not necessary if you just want a simple model to learn from. I wouldn't worry about a diode going to a 2nd battery because you can always add that later. It sounds like you could use more turns. The wire I buy is sometimes on like 10 pound spools of various sizes (and weights)...much cheaper per foot than the radio shack wire. You don't need an external ground.

I hope some of these things help.

[Shamus]

Hi Aaron!

As far as the coil goes, I followed the directions for winding as you set forth above. When I energize it with the (+) coming off the top lead and (-) off the bottom, it's a north pole with quite a bit of kick (I tested both the #24 portion and the #26 portion, and both are quite powerful as electromagnets ). I verified north on my magnets by hanging one on a piece of thread and seeing which side faced north, and labeled the side facing that way as "north". I then checked all the rest of my magnets by checking for repulsion with the known north face and labeled all the repulsed sides "north" as well. The core is made up of 2 1/2 inch nails epoxied together with the heads cut off, cut to length, and the points sanded down.

The components are the stock ones suggested by the schematic: A 2N3055 transistor, a 1N914 diode, and a 10 ohm, 1/2 watt resistor (too much wattage? seems unlikely to me). I'm using a battery consisting of 1.5V AA cells--one at 6V/2.3A, and another at 12V/8A. There isn't any deviation from what's suggested up above other than the lack of turns on my coil. Also, it doesn't induce enough current even if I give the rotor a good spin. Pictures follow. In the closeup of the circuit, the clips are not shorting out with the collector. I decided to go with clips after losing the second transistor and thinking that my diode had blown. This way, I can test components without having to solder/desolder anything.

Also, I connect (+) from my battery to the red lead coming from the top of the coil, and connect the (-) to the emitter (the clip on the bottom right of the circuit closeup). The second transistor blew when I gave the rotor a good spin and it acted as if it were magnetically braking the rotor--the coil and transistor heated up quite a bit on that run. I have since verified and reverified that the coil is hooked up correctly to the battery and that the coil produces a north magnetic field out the top that repulses each and every magnet on the rotor. The only thing that looks different in my setup is the number of turns on my coil, but there could be something else that I've overlooked.

[Shamus]

!!! Success !!!

OK, yesterday I finally tracked down a local supplier of magnet wire after I found out that the wire I ordered over the internet wouldn't arrive for TWO WEEKS. At any rate, I finally wound 600 turns of #22 and #26 on my core (after removing the 388 turns that were already sitting on it ), hooked up the alligator clips, and success!

Some preliminary tests showed interesting results. It went at a pretty good clip when I had the 12V battery hooked up, but it seemed to run faster with only 6V (going by the pitch the bearings were putting out). Curiouser and curiouser. The current draw was only about 1/4 of an amp with the 6V, which should go down once I replace the 10 ohm resistor with a 680.

Also, my coil runs hot too. So much so, that loosened the epoxy on the back side of the coil spool! My guess as to why it's running hot is that there's just too much juice going through it, which upping the resistance should help with--I mean, come on, 10 ohms isn't much. At any rate, I hope to post some more rigorous results here once I get my coil back together.

And oh... The questions, the questions... More later.