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KryptKrunch
Starting Member
United Kingdom
6 Posts |
 Posted - 05/09/2009 : 2:00:14 PM
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Hi teeps,
I was just wondering how you measure the voltage and amperage generated by the Bedini/Newman/Daftman machines. I know you can't use a MM, as it does'nt give a true reading. I think 99% of us dont have the cash to buy a oscilloscope.
If anyone can shed some light, i'm sure we all could gain a little knowledge.
Cheers, Krypt
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comwarrior
Moderator
United Kingdom
477 Posts |
Posted - 05/09/2009 : 7:24:16 PM
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that question is one of the hardest to actually answer...
i have 3 multimeters that have faults with the curent measurements all because my transister self distructed and shorted out while my DMM was set to 200mA range... or because the BEMF spike was too much for them...
How do you measure it... erm... the best acturacy way i can think of is to use a large capacitor and measure the time it takes to charge it upto a certain voltage... their is 'somewhere' the calculation to convert farads to amps... i've not looked for it but it IS on my mind to go search...
If you find it, post a link to the page on these forums, saves me spending hours searching...
I'm sorry i can't give you a direct answer... i don't think anyone can...
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"Energy can not be created nor distroyed, it can only be changed into other forms" - so lets do some changing!
95% efficiency, I dare you to do better!
http://www.youtube.com/user/comwarrior69 |
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Lorke
Junior Member
USA
58 Posts |
Posted - 26/10/2009 : 07:25:11 AM
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This I found on a separate forum, Author was known as "JohnS" He is responding to a fella wanting to use Caps instead of batteries for an electric bike.
X farads at 2.7 V is 2.7 X coulombs. However, there are 3600 s in an hour, so 2.7*X coulombs is 2.7*X/3600 Ah. Still worse, the capacitor voltage will decrease linearly as it discharges. A battery maintains a fairly constant voltage until it is almost discharged, then plummets to zero.
Real comparability would require looking at the total stored energy in joules. For the capacitor, 0.5*C*Vē, for the battery V*Amp hours*3600. You need 2700 farads, rated at 32 volts. If you connect 16 V packs in series, you'll need 5400 F in each pack. I recommend batteries. Supercapacitors aren't really super.
****Its like building a puzzle but you have never seen the picture, and you only get 3 pieces a week.**** |
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vesperhbt
Advanced Member
USA
445 Posts |
Posted - 26/10/2009 : 3:01:28 PM
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Well I have an answer for you. It is hard because of the difference in the caps use storage and discharge, but here you go.
A capacitor's storage potential, or capacitance, is measured in units called farads. A 1-farad capacitor can store one coulomb (coo-lomb) of charge at 1 volt. A coulomb is 6.25e18 (6.25 * 10^18, or 6.25 billion billion) electrons. One amp represents a rate of electron flow of 1 coulomb of electrons per second, so a 1-farad capacitor can hold 1 amp-second of electrons at 1 volt.
A 1-farad capacitor would typically be pretty big. It might be as big as a can of tuna or a 1-liter soda bottle, depending on the voltage it can handle. For this reason, capacitors are typically measured in microfarads (millionths of a farad).
To get some perspective on how big a farad is, think about this:
A standard alkaline AA battery holds about 2.8 amp-hours.
That means that a AA battery can produce 2.8 amps for an hour at 1.5 volts (about 4.2 watt-hours -- a AA battery can light a 4-watt bulb for a little more than an hour).
Let's call it 1 volt to make the math easier. To store one AA battery's energy in a capacitor, you would need 3,600 * 2.8 = 10,080 farads to hold it, because an amp-hour is 3,600 amp-seconds.
If it takes something the size of a can of tuna to hold a farad, then 10,080 farads is going to take up a LOT more space than a single AA battery! Obviously, it's impractical to use capacitors to store any significant amount of power unless you do it at a high voltage.
Applications
The difference between a capacitor and a battery is that a capacitor can dump its entire charge in a tiny fraction of a second, where a battery would take minutes to completely discharge. That's why the electronic flash on a camera uses a capacitor -- the battery charges up the flash's capacitor over several seconds, and then the capacitor dumps the full charge into the flash tube almost instantly. This can make a large, charged capacitor extremely dangerous -- flash units and TVs have warnings about opening them up for this reason. They contain big capacitors that can, potentially, kill you with the charge they contain. so be very careful with your dealings with them.
I really hope this helps out and good luck.
Sincerely
vesperhbt. |
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vesperhbt
Advanced Member
USA
445 Posts |
Posted - 26/10/2009 : 3:26:21 PM
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Okay now that you have this information lets make it simple to calculate for what ever you may be doing.
you have the formula so what is next break out the calculater and do the math right? Well not so fast lets make it easy. at the following address you can download a calculator for windows that I have used for years. it is great and the best thing about it is it can calculate any thing you may ever need.
http://joshmadison.com/software/download-convert-for-windows/
Then you can click on Options then preferances then custom and enter the formula above and then save this in the calulations field and then all you need to do is punch in the cap and the answer will be produced it is very simple.
Well enjoy let me know how you do?
Sincerely
vesperhbt. |
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Lorke
Junior Member
USA
58 Posts |
Posted - 26/10/2009 : 7:09:32 PM
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Nice, now I have an idea what the fella I 'quoted' is babbling on about. LOL
****Its like building a puzzle but you have never seen the picture, and you only get 3 pieces a week.**** |
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vesperhbt
Advanced Member
USA
445 Posts |
Posted - 27/10/2009 : 5:54:21 PM
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Ya I know I saw lots of rambling but had to do allot of searching to get the real data then form it into a realistic concept.
Also I have the formula inputs for the calculator in photos (don't know how to post photos here) to aid any one that may be interested. or shoot me an email and I will reply with the information.
vesperhbt
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Measuring the volts and amps?
