Electronic question

[Anonymous]

I have a question that's a little off topic but will start some ideas for trains.
Is it true that if you can get a capacitor to discharge all at once the voltage will be higher than what went in?
Also if this is true how do you get a capacitor to discharge all at once? (I won't electrecute myself. I know the dangers)
Thanks,
Scott

[cacole]

The answer to your question has so many variables that there is no concrete answer. What type of capacitor? How much internal leakage? How much applied voltage? The way to instantaneously discharge a capacitor would be to short the terminals together, but depending on the capacitor and amount of charge, this could be hazardous to your health. A capacitor used in an old television set, for example, could be charged up to a voltage of 25 to 30 thousand volts or more, and could be lethal. These capacitors would hold a charge for weeks after the set was unplugged. Television technicians had to be extremely careful that they didn't touch the anode of the picture tube or the capacitor, or they had to deliberately ground the capacitor and discharge it first. I saw one draw a 12" bolt of lightning off of one of these capacitors with a screwdriver. Most electrolytic capacitors are too low a microfarad rating to be dangerous, though, and you wouldn't get shocked even if you did touch the terminals. Such a capacitor wouldn't be dangerous until it got to be very large, such as the ones you sometimes see atop power line poles, of a high farad rating, and charged with a high voltage. Such a capacitor is rare and very expensive. Some capacitors can be used to increase voltage because they will build up and hold a charge. For example, I built a central power supply for the Cochise & Western Model Railroad Club's 20x40 foot HO scale layout that uses four 12 Volt 35 Amp transformers feeding power through large inductors and 15,000 microfarad, 100 Volt military surplus electrolytic capacitors in a Parallel Pi filter configuration; i.e., the output from two transformers in parallel goes through an inductor, into a capacitor, through a second inductor to a second capacitor, and then through a third inductor. The second bank of transformers are wired exactly the same and put their output through a parallel set of inductors and capacitors. The output voltage from these two parallel filter networks is then combined. The inductors and capacitors smooth the output from AC to DC, and also boost the voltage. The final output of this supply is 19 volts pure, filtered DC at 35 Amps. Even this high Amperage is not dangerous, however, and it is safe to touch the power supply's output terminals with your bare hands and receive no shock. Whether you are electrocuted or even feel a shock depends on a combination of high voltage and high amperage. If you have ever seen a Van Degraff Generator, the plastic globe with multi-colored electric sparks flying around on the inside where you can hold you hand up to it and the sparks chage, you are experiencing an extremely high voltage but at low amperage. The "lighting" in these devices ranges in the 15 to 20 thousand volt range but at only milliamps, so the voltage will not shock you. If the current was up to a range of 20 or 30 amps, that much voltage would kill you. Likewise, a high enough amperage and low voltage can kill, but even a car battery rated at over 100 amps at 12 volts usually is not enough to shock as long as you're not deliberately grounding yourself by touching the car body and only the positive terminal of the battery, thus making a completed circuit.

[Anonymous]

Wow, thats a lot of info. Thanks a lot.
Scott

[Anonymous]

Scott.

I din't read all of what was written above I got a headache after a while, however what I did read of it , it sounded pretty right and quite knowlegeable.

However could i ask, why do you want to do this? If you want to increase your voltage a filter capacitor across the circuit will help, also one in series will as well so you really need to tell us more about what you hope to achieve, besides blowing yourself up.


Thunder from Downunder.

[grandpopswalt]

The capacitor doesn't really increase the voltage, it merely increases the DC level. Example: if you measure the output of a transformer you are, in effect , measuring the "average" of the high and low points of the AC wave (somewhere between zero volts and the peak of the wave. So, a transformer that is rated "12 volts AC" has a peak output voltage of 12X1.4 or 16.8volts. If you put a rectifier and large capacitor across the output, you will filter out the valleys (zero voltage points) and cause the capacitor to charge up to the peaks. So if you now measured across the Cap you'd read 16.8 volts DC.

This is a very simplified answer which doesn't take into account a lot of other factors which would probably only serve to confuse the issue.

The circuit described in a previous post which uses multiple capacitors and inductors is sometimes called a voltage doubler and uses the property of storing out of phase energy in such a way that the output voltage is actually doubled. However, the current capacity of those circuits was relatively low.

And another point .......... voltage doesn't hurt you, current does. If you could levitate, you could touch a 138,000 volt power line and feel absolutey nothing, why?, because there would be no path for current to flow to ground. Voltage is only electrical "pressure", current is what you feel going through your hand when you stick your finger into a live lamp socket. Under rare and extremely unusual circumstances even a relatively low voltage can produce enough current in a human body to be lethal.

Walt

[Anonymous]

I was zapped with 138,000 volts back in 1999. I don't know the amperage tho. But was from a high tension wire. Anyone know how i can figure the amperage out?

Trevor

[underworld]

Conklin4Vez How did that happen??? You are very lucky to have survived that one.

underworld

[Anonymous]

Lanscaping, was holding a tree branch. Imagine holding it straight up like a clock, well at around 2 when i was pushing it down caught a wire above my head and got zapped. Pretty brutal, but no burns on my face just lots on legs and lower part of body.

[Anonymous]

To put it simply, a single capacitor will only charge to the peak voltage that is applied to it. Newbies in the electronics repair shops are initiated by the old hands by charging a 100 mfd. electrolytic capacitor, bending the leads next to each other, and throwing it to the newbie. Newbies can get real gun shy, quick![:-,] Never done it mself.[:-^][;)][:D]

[grandpopswalt]

Capt_Turk,

We're fortunate to have Capt. Carrales (the flying capt) and Capt. Johnson (the floating capt) contribute regularly on this forum. What type of Capt. are you, Capt. Turk?

Walt

[RhB_HJ]

QUOTE: Originally posted by grandpopswalt

Capt_Turk,

We're fortunate to have Capt. Carrales (the flying capt) and Capt. Johnson (the floating capt) contribute regularly on this forum. What type of Capt. are you, Capt. Turk?

Walt

He's a tug boat captain.

[RhB_HJ]

QUOTE: Originally posted by Conklin4Vez

I was zapped with 138,000 volts back in 1999. I don't know the amperage tho. But was from a high tension wire. Anyone know how i can figure the amperage out?

Trevor

Not really, except if it would have been a tad more you wouldn't be around today.

[grandpopswalt]

Capt_Turk,

Should have read your bio before posting my question. Sounds like you've lived a very interesting life. You should try to hook up with our Capt Johnson, he's a retired ship's pilot.

Walt

[Anonymous]

i should not even be around now, 138,000 is no small shock that's for sure. But i pulled threw somehow. Ok sorry to bother you folks here and sorry for ruining this thread.

Trev

[Anonymous]

On the way back after unloading..

This is what I had on the barge.

I'm one of them nasty ole tugboat drivers. Mostly offshore. This sure would make a great place for a layout! Photo of the barge I'm towing right now.
[4:-)]

[Anonymous]

Hey!!!!!!!! After the fourth attempt, I finally managed to post a picture!!![:D][:D][:D][4:-)]

[Capt Bob Johnson]

Walt,
We have discussed the possibility that we may have met.

Turk,
When you were on the PR run did you know or have the boat that was built for Seatrain and is now the "Janice Guzzle" of TECO's Gulf Coast Towing? Had her a few times up here in Philly!

[Anonymous]

Up till recently I have been the owner skipper of a 10 m off shore yacht, a North Shore 33 called "Itayne" but I had to sell her as I was retiring and it is a bit exxy on a fixed income and My knees weren't up to a heavy seaway.


Rgds ian

[wa1lbk]

"Newbies in the electronics repair shops are initiated by the old hands by charging a 100 mfd. electrolytic capacitor, bending the leads next to each other, and throwing it to the newbie. Newbies can get real gun shy, quick! Never done it mself."

Capt Turk, reminds me of my days (30 years ago) back in tech school! [:D][:-,] I had some previous electronics experience (mainly through ham radio) & used to be a perpetrator of the aforementioned stunt! [(-D] This was vacuum - tube days (kind of hard to do with all the modern low-voltage stuff), we had variable - voltage DC supplies on our lab benches (capable of up to 400 VDC out! [xx(] ) for powering tube circuits we built. Used to take an 80 MFD., 450 V. axial-lead electrolytic cap, bend the leads over so it was nearly impossible to hold it without touching both leads, & charge it to 400 V., then toss the charged cap to an unsuspecting newbie [D)] "Here, catch!" [:D][}:)][:P]

The newcomers learned very quickly NOT to catch! [B)][:O][;)] Tom

[Anonymous]

My stupid adventures go back to the fifties, when as a trainee telecommunications technician, "down the back" was called the skillion shed, because of its roof. We used to get two lead cable cases and suspend them from a rafter. To that we would connect it to a magneto out of an old magneto type telephone. We would leap up grab hold of the two cables and some one would wind on the magneto, wow it hurt. The winner was the idiot that could take the biggest charge for the longest.

No doubt this didn't last long, as we all one by one got interested in girls and this was deemed immature behaviour.


rgds ian