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View Full Version : I need help with a bedini


cody
01-26-2009, 10:31 PM
Over the past year or so i have made about 4 different motors, all using very basic switching, reeds, transistors, mechanical. Ive started trying to adapt my latest one to switch with a bedini circuit and i have a problem with it. I cant get the thing to stop self oscillating, it wont run the motor, it just gets itself going. This is cool and all, but i want it to run the motor, not self oscillate. So it either self oscillates or does nothing. I turn the wheel when its doing nothing to try and get the motor to start, but nothing happens. I thought maybe i had the trigger wire reversed so i changed it, nothing again and would not self oscillate either. On the other side of the motor i have some very strong neos for a generator, i wonder if the field from these are strong enough to effect the motor from properly triggering. Also using magnetite cores. Any comments or suggestions would be appreciated.

Jetijs
01-26-2009, 10:36 PM
Self oscillations usually occure when the base resistor value is too high. Try to lower the base resistance and see how it works.

cody
01-26-2009, 11:21 PM
Jetijs,
Ok, at first I had a 100 ohm base resistor. I changed it like you said, down to a 10 ohm, it didnt self oscillate anymore as long as the pot was down on its lowest setting. But its still not triggering at all. I give the rotor a spin and i get nothing. The magnets on my rotor are south facing, i know bedini uses north facing, but i would think you could reverse the trigger wires to get it to work:thinking: And i would think that because im getting a self oscillation that it must be hooked up right. Maybe ill have to reverse my rotor magnets :wall: Any more thoughts.

ren
01-26-2009, 11:24 PM
Cody, show us some pictures.
I have made little neo rotors that would self oscillate on startup (connection to source). Like Jet said this is usually due to too high resistance on the trigger wire. You can put a small 12v globe on the trigger wire too, it can help servo the trigger currents if they are too high. Give us your specs and we may be able to figure out what is going on.

Oh and also, if its small, give it a REALLY good flick. One of mine wouldnt start unless you really gave it some oomph, but that was most likely due to the tiny magnets I used and their spacing.

Joit
01-26-2009, 11:24 PM
When the Coils are singing, means your Circuit works.
Seems the problem is at the Power, what it can give to the Magnets, to turn it. Seems to weak , maybe you turn the coil?
Or try at backside with a ironsheet, how strong your magnet field is.
And the Frequency start low, mine usual works around 170-280, that it start.

Sephiroth
01-26-2009, 11:26 PM
Jetijs,
Ok, at first I had a 100 ohm base resistor. I changed it like you said, down to a 10 ohm, it didnt self oscillate anymore as long as the pot was down on its lowest setting. But its still not triggering at all. I give the rotor a spin and i get nothing. The magnets on my rotor are south facing, i know bedini uses north facing, but i would think you could reverse the trigger wires to get it to work:thinking: And i would think that because im getting a self oscillation that it must be hooked up right. Maybe ill have to reverse my rotor magnets :wall: Any more thoughts.

try briefly shorting the base and the colector... this should activate the coil and hopefully repel the rotor magnet. If it attracts the rotor magnet then turn you coil the other way around :D easier than turning the magnets over.

cody
01-26-2009, 11:53 PM
ren,
this motor is a bit of a frankenstien, its mainly an adams motor setup. I got 2 power coils on one side of the motor, series connected 1200 turns 18ga 3.4 ohm power wire. 600 turn 18ga 1.7 ohm series connected trigger wire. Basically i have 2 trifillar coils and series connected 2 wires of each for the power coil and series connected the remaining wire of each for the trigger. On the rotor for it i am using very weak magnets, you might be right here, i might have to give it a really good push.

Joit,
So far the circuit only works when its "singing"(oscillating). Thats the problem, it doesnt trigger at all by the magnets passing it, i know its not turning on, i have an amp meter hooked up to the draw side so i can see when its firing.

sephiroth,
I have been playing motors and coils long enough to know how to determine which side the positive and negative need to going to, but to double check, did as you suggested and it does repel. My concern about the south facing magnet was about how the trigger would respond because im not very familiar with using bedini circuits. My problem is that the trigger isnt being tripped by the magnets going by the coil, it is either doing nothing, or its self oscillating, regardless of the rotor being spun or not.

Sephiroth
01-26-2009, 11:58 PM
hmmm... well as long as the circuit is wired correctly, the only thing I could think of that would force it into oscilation at low trigger resistance would be either the pot is fried (more likely because you say it doesn't resonate when it is turned all the way down) or the 1N4001 is fried (less likely... they are quite robust) :thinking: can you test your pot?

dambit
01-27-2009, 12:10 AM
Hi Guys,

Sorry for putting this in this thread.

Seph,

Here is a picture of my setup using a timing led to see what position the magnet is in when the coil fires. Thought you could use it to prove your point. I have outlined the magnet and it direction of travel.

Cheers,

Steve.

P.S. Cody: Ditch the neo's for a start. Also, all of my motors have used south facing magnets because my coils are wound the other way. I have not noticed any difference in performance. It would help us a lot if we had a picture of your setup.

Cheers.

Sephiroth
01-27-2009, 12:16 AM
Hi Guys,

Sorry for putting this in this thread.

Seph,

Here is a picture of my setup using a timing led to see what position the magnet is in when the coil fires. Thought you could use it to proove your point. I have outlined the magnet and it direction of travel.

Cheers,

Steve.

Cheers Dambit... I was beginning to think I had gone just a little bit mad. Glad someone else agrees :thumbsup:

cody
01-27-2009, 12:16 AM
No no, its not oscillating at low resistance, but its still not triggering from the magnets. It self oscillates with high resistance from the pot. I just tested the pot and the diode and they are both good. The magnets on my rotor just dont get it to trigger, i wonder if its because they are so weak. And im still wondering if the other rotor on the other side (generator rotor)of the motor is screwing it up because it has very strong magnets and is in somewhat close proximity to my so maybe the field of those strong magnets is screwing up the field of my weak magnets?

gmeat
01-27-2009, 12:21 AM
Hi Cody,


Can you try triggering it with the neos?.You also may want to check each wire on both coils to make sure that you dont have any shorts between trigger wire and power wire.


-Gary

Joit
01-27-2009, 12:24 AM
Could be, that the other Field is to strong, imho.
You could place something like a Alloysheet between them.
It pretty eats the Magenticfield and slows the Rotor down, but it should isolate it, or maybe Iron, or a pice of the Metall from a Harddrive disk.
Or maybe move a stronger Magnet over your Coils, if they will do anything.

Sephiroth
01-27-2009, 12:28 AM
No no, its not oscillating at low resistance, but its still not triggering from the magnets. It self oscillates with high resistance from the pot. I just tested the pot and the diode and they are both good. The magnets on my rotor just dont get it to trigger, i wonder if its because they are so weak. And im still wondering if the other rotor on the other side (generator rotor)of the motor is screwing it up because it has very strong magnets and is in somewhat close proximity to my so maybe the field of those strong magnets is screwing up the field of my weak magnets?

It won't run if the trigger resistance is too low either... I could be wrong as I don't have your set up in front of me, but if I was having that problem I would test the pot...

cody
01-27-2009, 01:09 AM
Can someone tell me the least amount of voltage my trigger wire should be putting off in order for it to switch the transistor, im using a 2n3055. I think i might not be creating enough juice for it to trigger.

Joit
01-27-2009, 01:19 AM
Mine does work even with 0,2V and pretty low amp. should work very fast.

cody
01-27-2009, 01:45 AM
Ok i got it now. Due to the fact that i was using very weak magnets on my rotor and small cores in my coils, i wasnt producing enough energy to trigger the base of the transistor. I have added a separate trigger coil that is powered off my neos and its working now. Thank you everyone for helping me through that. I think i like this configuration better anyways because now i can adjust the pulse width with the bedini, and move my trigger coil to advance or retard the trigger beyond where the bedini normally triggers at. Just one more variable to play with.