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Registered Member #3834
Joined: Sun Apr 17 2011, 01:25AM
Location:
Posts: 2
hello, I'm new here, if your willing I'd like to pick a few minds about how to make a good ballast, i have a big a** transformer that I got from a torn apart stereo, and i heard that you can connect it in series with the mains and short out the other side of the transformer to make a ballast. is this a good idea? is there a better way? would a pot work better? I'm wanting to rectify mains power to power the driver and fly back for a plasma speaker, but in order to do that i need to be able to change the starting voltage on the go.
my ultimate goal is to make a plasma speaker that i can use in my room because my computer doesn't have any speakers -_-'. i have a cat though so could i make it safe by putting a metal food strainer over it and grounding it?
it'll be good to here about your guy's idea's and suggestions.
Registered Member #1875
Joined: Sun Dec 21 2008, 06:36PM
Location:
Posts: 635
It should work but plasma speakers designs typically are already current limited.
I'm not sure if it's a great idea to use a plasma speaker as a computer speaker for a few reasons, like interference, excessive power draw, and ozone/nitrous oxide production.
Registered Member #3781
Joined: Sat Mar 26 2011, 02:25AM
Location:
Posts: 701
Interference can be a problem, but usually only if the arc goes out and it is trying to re-arc - creating a lot of static electricity. It screwed up my LCD monitor until I unplugged it and plugged it back in. The ozone production should not be a problem unless you have a massive arc... I have a 4" inch arc and it produces a lot less ozone then my air purifier does.
Registered Member #3766
Joined: Sun Mar 20 2011, 05:39AM
Location:
Posts: 624
1. Air purifiers should not produce ozone, producing ozone does not purify the air, it just plays off the fact that people associate it with the smell after a lightning storm. pet peeve of mine 2. covering it with a strainer and grounding it would work, but if you're not careful it might try to arc to that instead, which is bad. curiosity kills cats. literally. 3. it's generally a lot easier to control a plasma speaker if you use a low voltage and wind a primary of 3-4 turns, this lets you use cheaper parts with the equivalent output voltage, and it's a lot safer to mess with. They usually don;t draw much current, <12A, I powered mine with a computer power supply, which I like because if it shorts out when I'm messing with half bridle and flack u, it shuts itself down. If you DO attempt to use rectified mains, use a GFI. Please. Mains is fun, but it can also mess you up.
Registered Member #3834
Joined: Sun Apr 17 2011, 01:25AM
Location:
Posts: 2
alright so normally a plasma speaker will ballast itself, if I'm messing with mains then i should use a GFI like the one in my bathroom. the Faraday cage would work unless it started arcing to the cage consistently then it'd be a problem. could i get around that by putting the contact in another cage under the Faraday cage?
would i be ahead to put a diode or a resistor in series with the head phones jack in case it wants to, for some reason, fry my computer with a few thousand volts?
since it is self ballasting when run off a lower powered source, i'm guessing a wall wart or something like that, would it be better for me to just use one of those or to integrate the ballast and power supply to the speaker. i am going to be using mains, that much is certain.
thankyou for the response, it's quite knowledgeable.
Registered Member #3610
Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506
Ozone does purify air, it oxidizes and breaks down some contaminates. It's also toxic though and corrosive, so you really don't want an air purifier to be producing it. On the plus side, the human nose is able to detect it in tiny concentrations so you don't need much of it to be able to smell it.
Registered Member #3781
Joined: Sat Mar 26 2011, 02:25AM
Location:
Posts: 701
Yeah, my air purifier does purify the air and it works. It says that it produces a safe amount of ozone (whatever that means). You are only supposed to leave the house if you put it on "sanitize" which probably means it produces a lot more ozone - to kill anything living in your house Although once when I was young, when I did not know what ozone was, I left it on in my room after I fell asleep... I woke up in the middle of the night coughing and it was hard to breath so I shut it off and went back to bed about an hour later; problem solved!
Registered Member #1875
Joined: Sun Dec 21 2008, 06:36PM
Location:
Posts: 635
Camp Badger wrote ...
Yeah, my air purifier does purify the air and it works. It says that it produces a safe amount of ozone (whatever that means). You are only supposed to leave the house if you put it on "sanitize" which probably means it produces a lot more ozone - to kill anything living in your house Although once when I was young, when I did not know what ozone was, I left it on in my room after I fell asleep... I woke up in the middle of the night coughing and it was hard to breath so I shut it off and went back to bed about an hour later; problem solved!
Registered Member #3429
Joined: Sun Nov 21 2010, 02:04AM
Location: Minnesota, USA
Posts: 288
waldosan wrote ...
alright so normally a plasma speaker will ballast itself, if I'm messing with mains then i should use a GFI like the one in my bathroom. the Faraday cage would work unless it started arcing to the cage consistently then it'd be a problem. could i get around that by putting the contact in another cage under the Faraday cage?
would i be ahead to put a diode or a resistor in series with the head phones jack in case it wants to, for some reason, fry my computer with a few thousand volts?
since it is self ballasting when run off a lower powered source, i'm guessing a wall wart or something like that, would it be better for me to just use one of those or to integrate the ballast and power supply to the speaker. i am going to be using mains, that much is certain.
thankyou for the response, it's quite knowledgeable.
First off, I don't know what you mean when you say that a plasma speaker will "ballast itself". That's not true because even a plasma speaker can draw too much current from the mains and pop a circuit breaker or fuse. The type of thing that you really need to ballast is any non-current limited transformer, such as an X-ray transformer. I've used a high wattage heater such as a hot plate or electric iron as a ballast, and they worked quite well. If the transformer acs over, or if a hv diode shorts out (for example) then the ballast will simply get hot! You do not need a ballast with a transformer that is current-limited such as a neon sign transformer or oil burner transformer.
Registered Member #3610
Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506
The few times I played with a dental x ray transformer the resistance of the (thin) mains cord and the droop of the variac were all the ballasting I used. It also quickly burned up the thin wire electrodes I used once an arc struck, but it was quite a sight. Arc self struck with a gap of about 5" and stretched out to over a foot long as the wires consumed themselves until I cut the power.
I have some HID ballast chokes a friend brought over from the UK that work great for this sort of thing. 400W mercury lamp choke is about 4A, and they can be paralleled. The US style HX or leak autotransformer ballasts would probably work too, keeping in mind that the 120V input ones step up the voltage.
For really high power, get a cheap "buzzbox" AC arc welder and short the output. Wire the input in series with whatever you are trying to vary, and use the current adjust knob on the welder to vary the inductance and control the output current.
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how do i make a good ballast?
Although once when I was young, when I did not know what ozone was, I left it on in my room after I fell asleep... I woke up in the middle of the night coughing and it was hard to breath so I shut it off and went back to bed about an hour later; problem solved!
