Hi, I'm a bit new to Transformers, but I do have some knowledge of electronics. I'm trying to convert 120V AC (a wall outlet plug) to 800V DC or more. Are there any devices out there that contain a transformer that meets my requirements? And costs close to nothing? I did however do a bit a research that an TV, microwave, or old computer monitor will do the trick. Is that true? Or do I have to buy one/make one?
I also have another question about capacitors, is there a way besides ordering in capacitors to get them (I'm speaking of 800V caps, 1000uF or higher in V or uF)? Again possible in TV's, microwaves, or old computer monitors? I'm sure most of you probably know by now what I'm up too. If this is in the wrong sections please move. Thanks in advanced.
Or maybe any other way for converting AC to 800V DC.
You didn't specify how much power or current you need. High-voltage supplies in TVs or computer monitors are a lot higher than 800V (15kV and more). You can probably take a common 12V step-down transformer and apply 120V to the secondary to give you 1200V output. Then build a full-wave bridge rectifier with some high-voltage diodes of at least a couple thousand volt rating, and some high-voltage rated caps to smooth out some of the ripple. This won't provide a lot of power so protect it with a fuse on the input or provide current limiting.
You could also build a DC-DC converter that's more efficient but is more complicated. I suppose you could use the high voltage section out of a computer monitor but you'll have to modify it to reduce the output voltage, or use a voltage divider on the output. Another possibility is using the power supply out of an old camera flash unit. And no, I don't know what you're up. You don't need DC in order to fry cats though.
You could also build a DC-DC converter that's more efficient but is more complicated. I suppose you could use the high voltage section out of a computer monitor but you'll have to modify it to reduce the output voltage, or use a voltage divider on the output. Another possibility is using the power supply out of an old camera flash unit. And no, I don't know what you're up. You don't need DC in order to fry cats though.
QUOTE (deviatorz+Apr 22 2006, 08:47 PM)
Hi, I'm a bit new to Transformers, but I do have some knowledge of electronics. I'm trying to convert 120V AC (a wall outlet plug) to 800V DC or more.
Well, the microwave oven transformer has output in range 1500 V and it has a sufficient power output (more than 600 W). Although it has not been projected for permanent power output.
Well, the microwave oven transformer has output in range 1500 V and it has a sufficient power output (more than 600 W). Although it has not been projected for permanent power output.
A bit of a clue as to what you're planning to do with your 800 volts would narrow down the type of power supply required a lot.
C2
C2
Sorry took to long to reply, getting caught up with school work. I'm trying to build a rail gun to be more specific. For power anything under 600W would do and current wouldn't matter cause that will count for time to charge the capacitors (slow wouldn't be a problem). Lol I'm going to use the school's power supply so yea lol. Definitely more than 800v could be used to build a rail gun (eg. 2kV or something), but if the power gets any higher that means I'll have to get a higher voltage capacitor = more money which I don't have, so I'm sticking with 800v since my last one with 300v worked, but inefficiently. Thanks in advanced.
I'm not quite sure what happens if you wallop 120 volts up the 12 volt winding of a 12 volt transformer .. I just have a feeling it won't be a good experience.
In my country we have 240 volt mains but I think all should be well for 120 volt mains. The insulation even on small transformers seems good to over a thousand volts (been there done that)
What I have done is take a 12 volt transformer and feed the output of that into a 3 volt transformer .. this will give you 4 * 120 Volts RMS (it gave me the 1000 volts RMS). You could play with 24 volt transformers and tappings etc. .. easy stuff. When you peak rectify you get 1.4 ish times the RMS .. so you are up in the right league already.
See http://www.wenzel.com/pdffiles/voltmult.pdf to take you into the unlimited league with cheap stuff.
I assume you already know about rubber soled shoes .. the other bit is
Always keep one hand in your pocket when working with high voltages.
Never assume anything is discharged .. you can discharge things .. and it comes back by itself
-C2
.
In my country we have 240 volt mains but I think all should be well for 120 volt mains. The insulation even on small transformers seems good to over a thousand volts (been there done that)
What I have done is take a 12 volt transformer and feed the output of that into a 3 volt transformer .. this will give you 4 * 120 Volts RMS (it gave me the 1000 volts RMS). You could play with 24 volt transformers and tappings etc. .. easy stuff. When you peak rectify you get 1.4 ish times the RMS .. so you are up in the right league already.
See http://www.wenzel.com/pdffiles/voltmult.pdf to take you into the unlimited league with cheap stuff.
I assume you already know about rubber soled shoes .. the other bit is
Always keep one hand in your pocket when working with high voltages.
Never assume anything is discharged .. you can discharge things .. and it comes back by itself
-C2
.
Hmm I see thanks.
I have done that to a 24V transformer once before and the insulation held OK. Working with this kind of stuff a lot I would think that a 12V transformer would stick it but just keep it fused and well earthed out.
Be very careful with capacitors. I once smoothed out the DC of a very low power air core transformer I had wound through a bridge rectifier with a capacitor on the end and forgot to discharge it. Picked it up a few minuets later and the 180 volts that the coil had charged it too hit me like a sledge hammer. Luckily it was not a huge capacitor but to say the least I take grate precautions around them now. Especially when working with really high voltage stuff like Tesla coils. 10000V from an ignition coil most likely not do you much harm and will power nothing but connect it to a capacitor and spark gap and it can light a mains bulb! Energy is very dangerous when stored in a capacitors.
It would be best to find a properly rated transformer or rewind your own appropriately with a layered winding construction so it wont blow. Cant think of any other appliances that use high voltage that have not been mentioned already. Sorry.
Be very careful with capacitors. I once smoothed out the DC of a very low power air core transformer I had wound through a bridge rectifier with a capacitor on the end and forgot to discharge it. Picked it up a few minuets later and the 180 volts that the coil had charged it too hit me like a sledge hammer. Luckily it was not a huge capacitor but to say the least I take grate precautions around them now. Especially when working with really high voltage stuff like Tesla coils. 10000V from an ignition coil most likely not do you much harm and will power nothing but connect it to a capacitor and spark gap and it can light a mains bulb! Energy is very dangerous when stored in a capacitors.
It would be best to find a properly rated transformer or rewind your own appropriately with a layered winding construction so it wont blow. Cant think of any other appliances that use high voltage that have not been mentioned already. Sorry.
Since a rail gun only needs to fire occasionally, a microwave oven transformer would be Ok as long as you have control circuitry to turn off the power to the Txfmr and disconnect it from the capacitor once the capacitor is fully charged. You should have a current control cct feeding the capacitor as well so as not to damage sucha large capacitor. (I've seen a 47000 uf / 500V cap blow. It is very reminicent of a shotgun blast.)
Once the cap is charged and ready you could fire the rail gun.
Once the cap is charged and ready you could fire the rail gun.
Great I see what I can do, thanks
I'm trying to design something similar, a 500 V, 200mA DC power supply. I didn't understand Confused2 idea for the transformers. How does putting the output of a 12V transfomer to the input of a 3V tranformer give you 4*120V?
Also how do I decide on the capacitor sizes and diodes to use. Like the guy before me, I'm trying to spend as little money as possible on these transformers. Thanks.
Also how do I decide on the capacitor sizes and diodes to use. Like the guy before me, I'm trying to spend as little money as possible on these transformers. Thanks.
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