Negative Polarity Power Source?

For Short Term Learning Discussions ONLY. This area is for CURSORY questions and connecting with other users ONLY. ALL technical contributions need to be made in the appropriate forums and NOT HERE. All posts are temporary and will be deleted within weeks or months. You should have already search the extensive FAQs in each of the forums before posting here as your question may already be answered.
Post Reply
Taylor Shead
Posts: 15
Joined: Sat Oct 20, 2018 4:09 am
Real name: Taylor Shead

Negative Polarity Power Source?

Post by Taylor Shead »

Hello

As a few of you may know, I am teaming up with Ben Barnett do build a demo fusor as a research project for the university we attend (UTA). He is an EE student and I am an ME student.

We have access to a couple of power sources:

#1:
Image

Image

#2:
Image

(I thought I had a picture of the front but apparently not)

I know we need the positive side to be grounded. I read a topic here that concluded that you can't just ground the positive. The supply needs an internal positive ground. Is this correct for a demo fusor?

Also it look like our option #1 can be reversed polarity but doesn't meet the amperage requirements.
Our option #2 almost meets the requirements for a fusion fusor but its polarity can't be reversed.


We talked about modifying #1 but I'm not sure our advisor will let us.


Can we make use of one of these for a demo power supply?


Taylor
Last edited by Taylor Shead on Sun Nov 18, 2018 12:56 am, edited 1 time in total.
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Negative Polarity Power Source?

Post by Richard Hull »

Regarding altering option #1. Usually all single polarity supplies like this are internally grounded to the case and power line ground in many places within the circuitry. This reduces required insulation internally.

Selectable polarity power supply units are far more highly insulated and place their grounding selector on a larger printed circuit board with pins, well isolated from each other on this "polarity selector switch board"

The polarity selectable supply might barely make a demo supply provided their is no current limiting. If their is limiting at 2.5 ma, then this will not work at all.

You might be back to a neon transformer homemade supply as a demo power solution.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Negative Polarity Power Source?

Post by Dennis P Brown »

For a demo fusor any power supply that allows the device to create a visible plasma meets your goal. Even a positive supply is absolutely fine for a demo device. Also, any low current supply is acceptable if it creates a visible plasma (like a NST.)

A demo fusor can be any level - even include deuterium gas for proper color but this device is only created to make an observable plasma.

Obviously, if one ever hopes to do real fusion in a fusor, a proper power supply (polarity, current and voltage) would then be needed and is a better approach for the demo since it will provide real experience handling both the voltage, current and issues of creating a stable plasma (assuming one is operating in the correct vacuum range.)

The power supply you show in the image is perfectly acceptable for a demo system. But that isn't a NST and that supply is dangerous; as such, careful precautions should be taken.
Taylor Shead
Posts: 15
Joined: Sat Oct 20, 2018 4:09 am
Real name: Taylor Shead

Re: Negative Polarity Power Source?

Post by Taylor Shead »

So if I used a power source with positive supply would I still wire the positive to the chamber and negative to the grid?
This is correct as I understand it but I want to make sure. We will likely stick with the bigger power source as it is cost effective. As for dangerous, we will be working in a room full of stuff that could kill us haha.

Fusion MAY be later (Summer 2019) but we are focused on the demo aspect currently.
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Negative Polarity Power Source?

Post by Richard Hull »

Ideally, the purpose of a demo fusor is to create a learning tool that is a look-alike and work-alike for a fusor. Only a negative hot, positive grounded supply will serve here.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Bern Bareis
Posts: 21
Joined: Sun Mar 29, 2015 10:40 pm
Real name: Bern Bareis

Re: Negative Polarity Power Source?

Post by Bern Bareis »

-30kV, 20mA supply Spellman DXM30N600X4215 for $500: viewtopic.php?f=20&t=12493
User avatar
Rich Feldman
Posts: 1470
Joined: Mon Dec 21, 2009 6:59 pm
Real name: Rich Feldman
Location: Santa Clara County, CA, USA

Re: Negative Polarity Power Source?

Post by Rich Feldman »

Hey Bern, it's good to see you helping out at fusor.net.
Done any work lately with your own fusor?
All models are wrong; some models are useful. -- George Box
Taylor Shead
Posts: 15
Joined: Sat Oct 20, 2018 4:09 am
Real name: Taylor Shead

Re: Negative Polarity Power Source?

Post by Taylor Shead »

Richard Hull wrote: Tue Nov 20, 2018 2:14 am reate a learning tool that is a look-alike and work-alike for a fusor. Only a negative hot, positive grounded supply will serve here.
So the negative hot is an absolute must? This will be difficult for us because we are on a time schedule. Most people aren't.
Bern Bareis wrote: Tue Nov 20, 2018 1:51 pm -30kV, 20mA supply Spellman DXM30N600X4215 for $500: viewtopic.php?f=20&t=12493

I'm pulling my hair out right now because I just saw this and it sold two days ago. I would have picked it up too. Oh well.
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Negative Polarity Power Source?

Post by Richard Hull »

If you really need fusor related stuff, a daily visit to the trading post is recommended.

That fabulous supply has been languishing, un-sold in the trading post since October 27th.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Taylor Shead
Posts: 15
Joined: Sat Oct 20, 2018 4:09 am
Real name: Taylor Shead

Re: Negative Polarity Power Source?

Post by Taylor Shead »

I couldn’t have purchased it until this week but now that money is gone. Our budget for the demo does not include a power supply. All I need to know right now is if there is ANY way we can use a positive supply.
John Futter
Posts: 1848
Joined: Wed Apr 21, 2004 10:29 pm
Real name: John Futter
Contact:

Re: Negative Polarity Power Source?

Post by John Futter »

for a demo fusor you can use a positive supply just as some use an AC supply ie neon transformer with no diodes
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Negative Polarity Power Source?

Post by Dennis P Brown »

As I posted (had hoped you might have read it), and Mr. Futter said as well, any polarity will work for a demo fusor. That said, if you have diodes, the definition of the cathode and anode are created by connecting the correct polarity to a given part of the fusor. The negative to the cathode; then by default, the positive is the anode. For a real fusor, of course, the anode is ground as well. In a demo, your choice to use diodes and then follow the design of a real fusor.
Post Reply

Return to “New User Chat Area”