Bedini Ferris Wheel Regauging Motor

[wrench76]

@ Les K
I did the math on John Bs figures, and I also got a total resistance of 1.822 ohms. Please forgive me if I misinterpret your post John. I believe only one slave coil was added in the equation."Now if I add all the coils together for a total I get this." JB
4.2, 1/x = .2348
6.368 1/x = .1570

So if that were the case,
4.2, 1/x= .2348 main
6.368, 1/x= .1570 slave 1
6.368, 1/x= .1570 slave 2
= 1/.5488 = 1.822
Again forgive me if I am wrong

Brian

[Les_K]

John, I appreciate your situation. I saw your last post was at 1:30 am. I hesitated to ask knowing how much effort you are putting in.
In other words take your time I am still a ways off waiting for parts.
Also I just looked last week and Jameco had the 3120 halls now they are all gone...Wonder how that happened?

Thanks again
Les

ooops! I just realized what you were saying John. You answered the question; I can just raise the resistance of the center coil, no need to waste your time testing.

Thanks Again
Les

[Les_K]

Les,
I would change the center coil to adjust that figure. This is not that critical 1.82 ohms may be a little to low for the switch. but I'm going to check that out, I will get back with you. I have some test circuits here. I'm just one guy here and getting a break at work at this time is questionable as to when. I will do my best.

John B

John, I appreciate your situation. I saw your last post was at 1:30 am. I hesitated to ask knowing how much effort you are putting in.
In other words take your time I am still a ways off waiting for parts.
Also I just looked last week and Jameco had the 3120 halls now they are all gone...Wonder how that happened?

Thanks again
Les

[John_K]

Thanks all

Thanks all for your responses.

The hall I was using was a 24V SS443A:
SS443A pdf, SS443A description, SS443A datasheets, SS443A view ::: ALLDATASHEET :::

The 15V Zener I am using is a 1N4744:

http://www.datasheetcatalog.org/datasheets/270/134194_DS.pdf

The hall triggers a MJE2955, which then fires the MJL21193/94 pair.

I will order the ATS137 as John B suggested, looks like they are the same one Rick sells. http://www.diodes.com/datasheets/ATS137.pdf


John K.

[BrentA929]

Bobbin sizes

John B,

Yes, I think we have the same bobbin sizes...

The large spool is 11" high and the slave spools are 5" high. Both spools have a 10.5" flange with a 3" barrel.

By the way, thanks for the numbers...I appreciate you taking the time to do those!


Thanks, Brent

Brent you say that your bobbin is very close to mine is that correct.

THE LARGE COIL,
Coil filled to almost 7/8 of the diameter with four wires Depending if your a sloppy winder like me. Holding 4 wires together as it does not make a difference.

I have chosen 2 # 15 wires at 4000 feet, now one wire is = to 12.736 ohms and two together = 6.386 Ohms.

Now, I have two # 18 wires at 4000 feet that = 25.54 Ohms from one wire. or two together at 12.77 Ohms.

Now I have two # 15 wires together at 6.386 Ohms
and two # 18 wires together at 12.77 ohms

If I use 1/X for the first number ( 6.386 ohms ) 1/X = 0.1565
if I take the second number (12.77 ohms) 1/X = 0.0783

Adding them together you get .23480 1/X = 4.258 Ohms for the big coil if all wires are tied together.

The big coil =, if you tie all wires together 4.2 OHMS

Outside coils #15 wire I have chosen 2000 feet = 6.368 Ohms each coil Can't Change that.

Now if I add all the coils together for a total I get this.
4.2, 1/x = .2348
6.368 1/x = .1570

Adding them together is .3918 1/X = 2.55 Ohms Total all coils together.

So the numbers are,big coil is Equal to 6.368 Ohms. Or if you tie all wires together 4.2 Ohms.

Slave coils ( outer Coils) 6.368 Ohms 2000 Ft #15 wire.

This is as close as I can get without taking the machine apart according to Rick's windings. I will bet this works just fine on that machine.
When all coils are added together you will have 2.55 Ohms or very close to that.
Oh I forgot to say if your duty cycle is correct with the timing you will have about 1.5 amps input current with that switch.

John B

[John_Bedini]

Bedini GT 3

Les,
I would change the center coil to adjust that figure. This is not that critical 1.82 ohms may be a little to low for the switch. but I'm going to check that out, I will get back with you. I have some test circuits here. I'm just one guy here and getting a break at work at this time is questionable as to when. I will do my best.

John B

[John_Bedini]

Bedini GT3

John K,
Use this Hall Mouser part Number.621-ATS137-PL -A - A this is the one that works the best.
It's a 24 V part.
John B

[Les_K]

small 3GT calculations

Based on John B's latest post I ran the numbers through my little spread sheet I made but don't know how to attach it here.
But this is how I am calculating this to match JB's numbers on a smaller version of the 3GT for anyone that may be interested and I hope it is helpful.
(I am guessing that the resistance values should be the same on a small machine as a large but I am not sure...)

I am calculating for a 1/4 scale version. so starting with the outer mags they are 1-7/8 x 3/4 x 3/8 "
Center core is 7 x 3" with a 3/4" core
side cores are 3.5 x 3 with 3/4 core

For the windings (calculations only as they are not wound yet)
Center core:
625 total length for each wire.
1 - #23 = 12.725 ohms
1 - #23 = 12.725 ohms
Parallel resistance = 6.3625 ohms
1 - #26 = 25.54 ohms
1 - #26 = 25.54 ohms
Parallel resistance = 12.753 ohms

Side coils:
313 feet #23 = 6.373 ohms with both in parallel 3.186 ohms.

With all in parallel 1.82 ohms.

John B, one quick question, I think you stated that the side coils can't be changed so Which would be the best values to adjust to get the resistance up to 2.55 ohms?


Thanks
Les

[Les_K]

Itsu or John B,

Can you please check to see if this is the way the zener should be connected? Reason being is that my circuit will not work properly this way. The way I see it is that the hall is getting 36V minus the voltage drop over the 1K5 resistor. This is causing the hall to self-trigger the circuit, when running at 36V.

I just popped the last of the 3 halls that Ren sent me, so will have to order some more before I can test this any further.


John K.

John K,
I am not sure about the data on your hall but the 3120 from jameco is rated at a fan out of 7. so it should handle a mps Ao6 just fine. but with a 750 ohm across the collector should reduce the current in the base as I think was suggested. and that should have solved the problem if that transistor is pulling to much current. I would think putting a zener in series on the output of hall might change the timing to much or alter the overall operation. sorry for piping in here but it looks like your little transistor is what's giving you the trouble.

Les

[gyula]

Hi John K,

Most of the linear Hall sensor ICs have an open collector output and whenever this output transistor is OFF its collector receives the full 36V (which can be any voltage up 38-39V in practice from three series batteries) and most probably this high voltage burns the output transistor (maximum breakdown voltage is exceeded too much).

The solution is to use a second 15V Zener diode in series with pin 3 output (the open collector), which will block at least half of the 36V+ battery voltage that comes in via R1 and R2 resistors (I refer to this schematic here:
http://www.energeticforum.com/attach...i-3gt-v1.2.pdf ).

This way both the supply Pin 1 and outpin Pin 3 can receive a maximum of 15V DC voltage, effectively save the Hall device from 36V+.

I just read Itsu post above. He is right when the Hall device just conducts current via Pin 3 but when it does not, the total 36V is present at Pin 3 via R1 and R2.

Gyula

EDIT: even a 20 or 22V Zener diode would be best instead of the 15V diode I suggested above.

[Itsu]

15 Zener OK

Hi John K,

yes this is the "normal" way to connect a zener to stabilyze a voltage.
Make sure your zener is a 15V zener, that way, you should measure 15V on the input of your hall (pin 1).

As you have 36V from the battery, you need to lose 36-15=21 volts acros the 1.5K resistor, meaning 14mA.
So the zener and resistor should be able to handle that current.

Are you sure your hall can handle the 15V (instead of your earlier 12V)?

Regards Itsu

[John_K]

Itsu or John B,

Can you please check to see if this is the way the zener should be connected? Reason being is that my circuit will not work properly this way. The way I see it is that the hall is getting 36V minus the voltage drop over the 1K5 resistor. This is causing the hall to self-trigger the circuit, when running at 36V.

I just popped the last of the 3 halls that Ren sent me, so will have to order some more before I can test this any further.


John K.

John K,

i guess John B suggested to stabilize your Hall this way:



Use a 15 V zener to keep the input of the hall at 15 V
Nevermind the strange type for the hall, my database did not have a hall symbol.

Regards Itsu

[John_Bedini]

Bedini GT3

Brent you say that your bobbin is very close to mine is that correct.

THE LARGE COIL,
Coil filled to almost 7/8 of the diameter with four wires Depending if your a sloppy winder like me. Holding 4 wires together as it does not make a difference.

I have chosen 2 # 15 wires at 4000 feet, now one wire is = to 12.736 ohms and two together = 6.386 Ohms.

Now, I have two # 18 wires at 4000 feet that = 25.54 Ohms from one wire. or two together at 12.77 Ohms.

Now I have two # 15 wires together at 6.386 Ohms
and two # 18 wires together at 12.77 ohms

If I use 1/X for the first number ( 6.386 ohms ) 1/X = 0.1565
if I take the second number (12.77 ohms) 1/X = 0.0783

Adding them together you get .23480 1/X = 4.258 Ohms for the big coil if all wires are tied together.

The big coil =, if you tie all wires together 4.2 OHMS

Outside coils #15 wire I have chosen 2000 feet = 6.368 Ohms each coil Can't Change that.

Now if I add all the coils together for a total I get this.
4.2, 1/x = .2348
3.1841/x = .3140

Adding them together is .5489 1/X = 1.82 Ohms Total all coils together.

So the numbers are,big coil is Equal to 6.368 Ohms. Or if you tie all wires together 4.2 Ohms.

Slave coils X 2 ( outer Coils) 3.184 Ohms 2000 Ft #15 wire.

This is as close as I can get without taking the machine apart according to Rick's windings. I will bet this works just fine on that machine.
When all coils are added together you will have 1.82 Ohms or very close to that.
Oh I forgot to say if your duty cycle is correct with the timing you will have about 1.5 amps input current with that switch.

Thanks for catching that Wrench76

John B

[BrentA929]

Bedini GT3

John B,

Sure...I'm not going to turn that down!


Brent

Brent,
If you want me to calculate it for you I will. I can do this easy.
John B

[BrentA929]

Bedini GT3

John B,

You are more than gracious to continue to answer my questions!

I appreciate all that you do for us and your willingness to share. I am like a kid waiting for Christmas morning as we wait for our spools to arrive to start winding them.

As far as circuitry goes, I think we have most of the parts, similar to what John K has done . We will know more when we get there. Just waiting for the spools!


Thanks again, Brent

Brent,

The coils are 1/2 The size of the big coil, 1/2 the resistance, When the meter is back I will give the measurements in ohms. The big coil has 4 wires depending on how you hook them up would lower the DC ohms.
RS seems to know the answer, so I will start over with numbers for you.
I do not trust the other meters so hold on.

THE CORE
We did a measurement of the core it is 3 inches The center coil with the core is almost 204 pounds. As I said The core is 3 inches out of the bottom of each coil. The welding rod is heavy as you will find out. The machine is not that critical to make work I will bet it works the first time even if your coils are a little off. Have you decided how to switch the output yet?

Calculating the coils is a ball park range so have a little extra wire. The most Perfect Things in the world never work, you end up changing them. Calculated circuits never work right off you must tweak them too. DO NOT worry it will work. I will make exact measurements for you as soon as the bridge is back. To bad you were not there as you could have measured what you wanted to. I can not take the machine apart so I will do my best.
Have no fear it will work..........
John B