Alternator / General Science and Electronics / Forums

Forums

4hv.org :: Forums :: General Science and Electronics

« Previous topic | Next topic »

Alternator

previous 1 2 3 4 next

Move Thread

LAN_403

Marko

Sat Feb 25 2006, 12:13PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Just most ordinary fuse will make 100% protection, if your house has any fuses in its fusebox then its silly to worry about burned instalations or etc.

As conner said, connect heater in series, you will have little less power but you cannot make more damage than heater itself can...

You can limit the current with any resistive, capacitive or inductive load, or use isolation transformer, so this is really silly thing to worry about...

the_anomaly

Sat Feb 25 2006, 01:22PM

Registered Member #19 Joined: Thu Feb 02 2006, 03:19PM
Location: Jacksonville, FL
Posts: 168

Why not just run it from your variac. Then itâ€™s not like its plugged directly into the wall and you have the same affect as running off an alternator. If your dad lets you use a variac then thereâ€™s almost no difference than the mains except if the variac has a fuse then you don't have to worry about damaging the house wiring.

wrote ...
Then, it's a mathematical fact that you can't possibly do more damage to the wiring than the electric heater would have done on its own, unless Ohm's Law isn't working that day.
Mike

but if you wire the project with the heater, then won't the heater element heat up and the resistance will go up. Although I doubt that matters if you want more current limiting.

scuba14c

Sat Feb 25 2006, 04:23PM

Registered Member #236 Joined: Wed Feb 22 2006, 09:59PM
Location:
Posts: 13

It is wired in with the variac, but I still can't touch the mains. I don't have a heater, either. Is there even a chance a small alternator would work?

Marko

Sat Feb 25 2006, 04:48PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

No. this must be a huge alternator, hooked to huge motor (both about etc. 1kW) and speed must be high enough to make 50Hz (around) and still generate wanted voltage.
So chance to find such things is really small.

If you really wish to power it from battery make some simple DC/AC inverter, using 2N3055s as said

With lots of transistors and one bulky transformer you could push few hundreds of watts and power the mot..

Variac usually has its own fuse, + house fuse, you can add your own and chance that something happens to mains iz zero.
Adding islation transformers or current limiting will also help.

I hope you have a 100 watt bulb in your house, connect it in series with mot, or few bulbs in paralell if you need more current.
Even if mot shorts bulb will just stay lit and nothing else will happen.

There are so many solutions for the problem but some alternator + motor seems really worst idea

HV Enthusiast

Sat Feb 25 2006, 04:49PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

Instead of trying to circumnavigate your parent's requests by dreaming up complex schemes, why not just sit down with your parents and discuss what you would like to do, and what benefits you hope to accomplish from your experiments. I'm sure if you took the time to sit with them, show them exactly what you want to do, how you wish to accomplish it, what measures you are taking to ensure safe operation of both the equipment and yourself, that you and your parents can come up with an amiable solution to the problem. If the answer is still no, then ask them what it would require to allow you to do the said experiments. If the answer is still no, then just accept act responsibly and accept your parents decisions and move on to another project.

scuba14c

Sat Feb 25 2006, 06:20PM

Registered Member #236 Joined: Wed Feb 22 2006, 09:59PM
Location:
Posts: 13

Eastvolt, that sounds like a good idea. But now that I have started the project, I sort of want to finish it, though not with the same power requirments. I tested a small unit and got around 11V AC. Just hooked to a drill and a few magnets, it worked better than I had expected.

HV Enthusiast

Sat Feb 25 2006, 10:08PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

Is it a project that your science teacher at school would endorse? If so, you may be able to test and run it at school under his supervision.

scuba14c

Sat Feb 25 2006, 10:30PM

Registered Member #236 Joined: Wed Feb 22 2006, 09:59PM
Location:
Posts: 13

I doubt the school would let me. With over 2100 kids, I think they would see the word lawsuit right away.

Omicron

Sun Feb 26 2006, 02:26AM

Registered Member #131 Joined: Fri Feb 10 2006, 09:25PM
Location:
Posts: 185

If you have parents annd are living with them a MOT is not a good project. Start with something simple like a Van De graff gen. Scitoys.com has simple HV things you can do. now lets lock this thred! You have your whole life ahead of you dont end it now.

Tesladownunder

Sun Feb 26 2006, 07:01AM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

Just my 2cents worth. It is important to keep your parents onside (I am one and have teenagers). MOT's are really risky despite how common they are.

For what you want a small 12 V plugpack or battery charger may be acceptable with a small transistorised inverter. Possibly with a 12V battery as well. It may be a lot safer but just take longer to charge.

The mains safety issue is trivial beside the risks of a MOT or the cap bank that you propose.

I don't believe that old house wiring is an excuse. If it is, the old perishing rubber stuff in metal conduits it is dangerous to the whole house and family even if no power is drawn and there will only be partial protection with RCD's and fuses. It should be replaced.

The cap bank is a separate issue. Presuming you want to do what most people do, ie make explosions, and run coil or railguns then don't forget that electrolytics do not like voltage reversal , which needs to be caught by heavy diodes or your caps are at risk. They are not pulse caps and will not like the high currents.

This is not a school project. Those energies have risks of explosion of wire, electrodes and the caps themselves, as well as the flash and bang. And that is without being concerned about the electrical shock hazard from exposed equipment.

If you do end up using a MOT, leave it in the MO cabinet, keep the fan, light, protection circuit and door interlocks. THis keeps it safer (hopefully) and also less unfamiliar to technophobic parents.
Eg the pic shows a 10 kV supply and a twin ignition coil supply run off the in-situ MOT.

Peter
(PM me if you want to discuss it confidentially)

previous 1 2 3 4 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob