Re: HELP With Step-Down Transformer and Converter

Dear Phantom,
I have broken-down what I need as follows:
A. 2 Volt Lead Acid Gel Cells, RAted 25 ampere-hours (6 pcs)
B. 12 Volt Cylindrical Battery (1 pc), looks like a big AAA Batery
right?
C. Ammeter, DC responding (1 pc)
D. Switch for the safety disconnect
E. 5000 amp shunt (1 pc)
F. millivoltmeter
F. Circuit Breaker 12 Volt DC-Rated, 750 Amp (1 pc)
G. 12 Volt Charger (AC to DC)

Series Connection When Charging:
AC Outlet >>>>> Charger >>>>> +Battery #1- >>>>> +Battery#2+
>>>>>+Battery#6-

Parallel Connection when Generating High Current
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
| | | | | | |
Battery#1 Battery#2 Battery#3.....Battery#6 Cir.Breaker====| Ammeter
|_ _ _ _ _ |_ _ _ _ _|_ _ _ _ _ _ _ _|_ _ _ __| |_ _ _|

1. Where do I put the Switch, Shunt and Millivoltmeter in the diagram
above?

2. Do you mean that I should dissect the 12 Volt Cylindrical battery
and use the wires inside it as connectors to the Lead Acid Batteries?

3. Although I can get very high current in the above setup, my voltage
would exceed the 0.90v to 1.50v range that I wanted, isn't it?
Basically, high current is generated by shorting the battery, is this
right?

4. If I decide to have a high DC Current and still maintain the DC
Volts at 0.90v to 1.50v range (to test faraday's induction law), I can
still use the design for the primary and secondary coil you provided,
right? Then I would need an interruptor to induce high current, right?
What should I use for an interruptor or where can I buy one? Is it
the same as pulsed DC?

I tried using a 12Volt Cylindrical BAttery some time ago and had a
smaller model with a thin Primary and a thick Secondary but I was not
able to induce a higher current in the secondary. My research tells me
that what I need is an interruptor that will correctly turn the primary
circuit ON/OFF at precise time. I used an ordinary ON/OFF switch as my
interruptor but nothing happens.

Gene


The Phantom wrote:
> On 19 Sep 2005 13:29:52 -0700, "gene" <winapps2@xxxxxxxxxxxxxxx> wrote:
>
> >Dear Phantom;
> >
> >I can't thank you enough for your help.
> >Don't worry, I will be careful. I will stand in another room holding
> >the switch, wear goggles, leather gloves, and all the necessary
> >precautions. I know it is dangerous to handle such high voltage.
>
> Actually, it's high *current*, not high voltage you're dealing with in the DC setup, and
> in the AC setup the high voltage (240 volts) is only on the primary side of the
> transformer. But really high currents pose a danger of a different sort. You won't get
> electrocuted or even shocked by the high current circuits you propose to create. The
> danger is molten metal splattering around.
>
> >I have my camcorder setup to record evrything that happens so I really
> >don't need to be close.
> >
> >Your assumption is correct. I only want to get a high current in a wire
> >for its
> >magnetic effects, and not to drive a load, and YES, I would not mind
> >spending some money on it.
> >
> >In the Dc-Dc setup using gel cells, do I need to have an interruptor?
>
> Your are thinking that you need an "interruptor" to get the DC to provide "transformer
> action" so it can be stepped down in voltage and up in current. With the lead acid
> battery, this is not needed because a transformer is not needed. This is why I recommend
> the gel cells rather than a DC-DC converter. It's much simpler.
>
> But, remember in my previous post, I said:
>
> "You must have some disconnect device
> in series with the battery (near one terminal of the battery), such as
> a DC rated circuit breaker:
> http://www.solarseller.com/dc_circuit_breakers_12_volts_to_125_volts.htm
> or fuse."
>
> That's a type of "interrupter", but it's not to get "transformer action". It's more
> commonly called a "disconnect". The idea is that if anything goes wrong while the
> experiment is running and some of the wiring becomes red hot (this has happened to me as a
> teenager. We all learn some of these lessons the hard way), when you panic and try to
> undo the bolts connecting the wiring to the battery, you discover that red hot wires burn
> you. You need a disconnect so that all you have to do is flip the switch and everything
> is turned off. The disconnect should be the first thing in the circuit connected to one
> of the battery terminals where no other wire can bypass around it. What I am recommending
> is that you use the big DC rated circuit breakers as switches to turn the current on and
> off, and since they are breakers too, they will automatically disconnect if the current
> gets too high. If you chose to use a fuse for the current limiting function, you must
> still have a switch there for the safety disconnect. That's the advantage of breakers;
> they are switches too. (Such high current fuses are expensive, by the way.)
>
> In your high current experiments the danger of molten metal comes from making
> connections when the circuit is energized. When you touch two pieces of metal which will
> carry 3000 (or even 750) amps when the connection is made, the sparking at the point of
> contact can splatter molten metal. You should turn off the breaker or switch while making
> the connections to the ammeter and whatever else is in the high current circuit. This is
> just common safe practice when working with electricity. Don't work on energized
> circuits. Hook everything up the way you want it, *then* turn on the switch or breaker.
> If you made a mistake and too much current passes, the breaker will open and avoid serious
> damage. Then you have to troubleshoot your setup and figure out what you did wrong.
>
> For your AC setup, the house breaker in the 240 volt circuit will provide the safety
> disconnect in the event of a short circuit. If you build the transformer I described, you
> should mount it in an appropriate electrical enclosure (box) with a switch on the primary
> (240 volt) side so you can turn it on and off while you're working on the high current
> side without having to run to the house breaker box. You don't want to have to provide a
> switch on the 3000 amp secondary side; it would be very big and expensive and it's not
> necessary. Just turn off the 240 volts to the primary of the transformer when you're
> working on the high current side. The breakers in the house service entrance are often
> not designed to be used as switches for many on-off cycles anyway, so the extra switch
> takes the wear and tear off the house breaker.
>
> >I understand that if I use AC, I do not need an interruptor since AC is
> >already turning ON and OFF by itself, but in a DC setup, shouldn't I
> >have an interruptor to induce a high current on the secondary?
>
> The DC setup I described doesn't need an interruptor. It doesn't have a transformer and
> so there isn't a secondary; there's just the battery. The lead acid cells can put out a
> very large current on their own. Have you ever shorted a car battery accidentally when
> connecting jumper cables? When you start your car, the battery is supplying hundreds of
> amps to the starter motor. Lead acid batteries are dangerous because of the high currents
> they can supply. Most modern cars have a plastic sheath that covers the terminal(s) of
> the battery, because if you are working on your car and accidentally drop a wrench across
> the terminals of the battery without that sheath, you get a most impressive fireworks
> display!
> >
> >To Answer your question on the soldering gun:
> >How do you know you didn't get high current? How did you try to measure
> >it?
> >>>> I used a tester to measure the tip of the soldering gun.
> >
> >If you got heat, then you got high current.
> > I maybe using the wrong equipment to measure current... like the AC sensitive ampmeter you suggested.
> > I was just wondering, if the soldering gun produces a high current at it's tip,
>
> The high current is only in the tip; it doesn't get into the thing you're soldering.
>
> > would it not short circuit the CHIP that one is soldering or would it not electricute the user holding the lead?
>
> The soldering gun has essentially the circuit I described for your AC setup. It's just
> a transformer with a single shorted turn of very heavy conductor for a secondary. If you
> remove the actual tip that does the soldering and measure the voltage at the bolt-on
> connections, it's probably quite low. My own Weller soldering gun has .35 volts open
> circuit at the bolt-ons, and .24 volts when the tip is in place. That voltage isn't
> enough to hurt anything. The current in the tip of a 100 watt gun must therefore be about
> 100/.24, or about 400 amps. But the reason that can't hurt you is that the 400 amps can
> only flow in the copper tip, not in your body nor in the thing you're soldering. It takes
> much more *voltage* to cause that much current in a human body (thousands or volts,
> although it doesn't take 400 amps to electrocute a person so a much lower voltage than
> thousands can electrocute, but .35 volts is completely harmless through skin). Only a
> virtual short circuit, such as provided by the heavy copper tip on the soldering gun can
> cause that much current when only .24 volts is available to "push" the current.
>
> >
> >What is a rare earth magnet? Where can I buy one?
>
> A rare earth magnet is a magnet made from mixture of substances which include what are
> called the "rare earths". The elements samarium and neodymium are the two most common
> rare earth elements used in modern magnets. These magnets are *very* strong, and the big
> ones can hurt you by pinching you really hard when a couple of them smack together on your
> fingers. You can buy them at:
> http://www.wondermagnets.com/cgi-bin/edatcat/WMSstore.pl?user_action=list&category=Magnets_and_Magnetism%3BPermanent_Magnets%3BNeodymium
> Get a couple at least of number 0013 and several number 0016 and whatever else strikes
> your fancy. They are fun to play with! Don't let them get close to your watch, your TV
> or your computer monitor or any floppy disks; and especially don't let them get close to
> your credit cards. They will erase the magnetic strip on the card; don't even hold a
> magnet in your hand and drop your hands down to your waist near a pocket with your wallet.
>
> >Lastly, Mike suggested that I should just buy a portable harbor freight
> >220V spot welder... Does this portable welder use DC as source? Is
> >MIke correct in saying that I would achieve and be able to measure the
> >same high current induction?
>
> The designation 220V means that it gets its power from the 220 volt AC coming into your
> house. I wouldn't know what it does after that without seeing a spec sheet, but Murphy's
> law says that it won't do what you want.
>
> >
> >My deepest gratitude to your efforts in helping me.
> >
> >Gene

.

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