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Registered Member #1886
Joined: Sun Dec 28 2008, 02:55AM
Location:
Posts: 73
I recently got a big transformer that supposedly came from an electron microscope and I'm wondering if anyone here knows more about it. The transformer itself only has a small label with ((CHI-5014 corona magnetics inc. 909-735-7558 9946)) on it. The ebay listing claims that the output should be around 32,000 volts and 20ma, but I have no idea what the actual current rating/VA rating is. It has one thick GTO wire poking out, the 2 primary inputs right by each other and an uninsulated terminal by the core which is the other part of the secondary. I haven't powered it up yet because I don't know if it needs to be ballasted/current limited etc and I don't want to accidentally fry it. The ebay listing Pics
Registered Member #561
Joined: Sat Mar 03 2007, 02:46AM
Location: Adelaide Australia
Posts: 230
From what he said in the listing it looks like he was only guessing the output current, I'd say it's about a 5ma transformer myself. But don't take my word, wait and see what the other users of this forum say
Registered Member #397
Joined: Wed Apr 19 2006, 12:56AM
Location: Western Washington
Posts: 125
I actually bought some stuff from the guy and chatted with him a while. He has all sorts of cool stuff, like a self-fabricated machine that'll cloth wrap wire and a ton of ham/transmitter stuff.
I'd contact Larry and ask him if he remembers the model # of the electron microscope he removed it from, might give you more useful information.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
I'd say power it up ballasted by a shorted NST (if you have one) or just anything that limits the current to a safe value (fluorescent ballast? the choke type).
If its really 32kV, be prepared it can spark over a distance greater than 5cm.
Also you could tell us the primary resistance and voltage, I can then tell you approximate power rating.
Registered Member #1886
Joined: Sun Dec 28 2008, 02:55AM
Location:
Posts: 73
Dr. Kilovolt wrote ...
I'd say power it up ballasted by a shorted NST (if you have one) or just anything that limits the current to a safe value (fluorescent ballast? the choke type).
If its really 32kV, be prepared it can spark over a distance greater than 5cm.
Also you could tell us the primary resistance and voltage, I can then tell you approximate power rating.
The primary voltage is 120V and the resistance is .5 ohms. For comparison my 15/60 NST's all have a primary resistance of .7 ohms. In the morning I'll try powering it up with a shorted 9/30 NST limiting the current and see what happens.
Update: Tested it this morning and it worked without any issues. I used a shorted 9KV 30mA nst to limit the current and had some fun drawing arcs with it. I still don't know the current rating though or how far I can push this. Here's a short video ;)
Registered Member #1159
Joined: Fri Dec 07 2007, 02:10AM
Location: Hudson Valley of NY State
Posts: 84
Nice video, Coherent.......PLEASE tell me you weren't holding the wire with 32 KV IN YOUR BARE HAND. A tiny crack or a pinhole that you couldn't see and it's all over. I think a piece of PVC pipe would be in order.
Registered Member #1886
Joined: Sun Dec 28 2008, 02:55AM
Location:
Posts: 73
sparky99 wrote ...
Nice video, Coherent.......PLEASE tell me you weren't holding the wire with 32 KV IN YOUR BARE HAND. A tiny crack or a pinhole that you couldn't see and it's all over. I think a piece of PVC pipe would be in order.
Please be safe....
Bob
I had the heavily insulated wire tied to an insulated screwdriver with a nylon tie. Also I inspected the wire before powering the transformer up and the insulation was in perfect condition. In any event I was only drawing like <10mA from the transformer so I didn't feel like getting the old 4 foot chicken stick out. I still have no idea what this thing is actually capable of though. It weighs 54 pounds and might be good for 30mA or higher for short periods of time.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Nice sparks, what's better than a high voltage apparatus in the bed!
I guess it should be good for ~1kVA continuous, 2kVA intermittent. I would try powering it with the output shorted and adding NST ballasts one at a time, leave it going for at least an hour every time while monitoring the temperature.
Registered Member #2018
Joined: Tue Mar 10 2009, 09:56AM
Location: Switzerland
Posts: 74
Looks like an x-ray-hv-transformer. From the core size it will easely take 1kVA for continous runs, much more for short runs. I would ballast it with a shortened micro wave oven transformer, this is more efficient than a shortened neon sign transfomer. You could also check the voltage, if you feed just 1V from a variac into the primary and measure the output voltage with a normal multimeter. You could calculate the winding ratio then and determine the exact output voltage for 120V input. The transformer seems to be resin potted, so you don't need any oil. This is a great advantage. Nice deal
Registered Member #1886
Joined: Sun Dec 28 2008, 02:55AM
Location:
Posts: 73
kilovolt wrote ...
Looks like an x-ray-hv-transformer. From the core size it will easely take 1kVA for continous runs, much more for short runs. I would ballast it with a shortened micro wave oven transformer, this is more efficient than a shortened neon sign transfomer. You could also check the voltage, if you feed just 1V from a variac into the primary and measure the output voltage with a normal multimeter. You could calculate the winding ratio then and determine the exact output voltage for 120V input. The transformer seems to be resin potted, so you don't need any oil. This is a great advantage. Nice deal
Greets kilovolt
The shorted MOT ballast really doesn't do a very good job. It pulls like 22A from the wall and puts out big 5''+ flaming arcs. Cool, but probably not good for the transformer. Right now I'm running it with a big space heater limiting the current to around 8amps, but it really weakens the arcs and the heater is making the room uncomfortably hot and wasting a ton of the power. Would two shorted MOT's with the primaries in series do a better job or should I use something else? The bulky space heater ballast sucks.
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Anyone know more about this big transformer?
