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Registered Member #2038
Joined: Fri Mar 20 2009, 03:39PM
Location: Bristol Uk
Posts: 60
I think that the self oscilating SSTC would be a better option for me. Can anyone point me to a decent website where i can find out a bit more about designing one? i'm not really looking for step by step instructions, and dont want a site that gets too carried away with the theory. but a site that lays things out in plain english, something a bit like the info on SGTC's here :
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
twist2b wrote ...
I know they don't last FOREEEVER, but they last longer then batteries if used correctly, and will always FULLY charge... batteries have gaps.
I know they have VERY little charge unless in really high ranges ( I think they said a high Farad ranged capacitor thats triple the size of a AAA battery will last 1/8th as long )
WHat I was thinking about though, is MIT's new technology... it can hold LARGER amounts of charge, and act more like a battery. Not perfect yet, but interesting technology.
The 942c's are impressive though :o
I am almost certain capacitors will never replace batteries, unless someone comes up with a super crazy capacitor. I mean, a single AAA is probably good for 5kj or something. If you can make a capacitor that can hold that much in that size, *whistles*. As you said, capacitors charge quick. They also discharge quick, but with high current. This sounds good, but a super capacitor the size of a AAA would only last like 50 seconds with a 1 watt load. If a AAA is indeed around 5kj, that would be 5000 seconds with a 1 watt load. I am willing to bet it is more than 5kj though.
Anyway, he did not lie about the sample, so what is the big deal? I would agree you should not start a thread (I've been down that road too though) about it, that might make others want to sample. I would simply say he did nothing wrong, just prevent other threads about samples from being opened?
Registered Member #33
Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971
Arcstarter wrote ...
twist2b wrote ...
I know they don't last FOREEEVER, but they last longer then batteries if used correctly, and will always FULLY charge... batteries have gaps.
I know they have VERY little charge unless in really high ranges ( I think they said a high Farad ranged capacitor thats triple the size of a AAA battery will last 1/8th as long )
WHat I was thinking about though, is MIT's new technology... it can hold LARGER amounts of charge, and act more like a battery. Not perfect yet, but interesting technology.
The 942c's are impressive though :o
I am almost certain capacitors will never replace batteries, unless someone comes up with a super crazy capacitor. I mean, a single AAA is probably good for 5kj or something. If you can make a capacitor that can hold that much in that size, *whistles*. As you said, capacitors charge quick. They also discharge quick, but with high current. This sounds good, but a super capacitor the size of a AAA would only last like 50 seconds with a 1 watt load. If a AAA is indeed around 5kj, that would be 5000 seconds with a 1 watt load. I am willing to bet it is more than 5kj though.
A typical good AAA battery stores a bit over 5kJ indeed, but this is just one side of the picture. The capacity of most battery types, including alkaline, drops dramatically as the load current increases. Good alkaline AAAs are usually rated at 1200mAh, but the real capacity might only be a third of that figure if you draw half a watt continously from it. According to this datasheet , a typical good AAA will last for 0.2 hours (or 12 minutes, or 720 seconds) when loaded with one watt.
Capacitors replacing batteries in many applications is certainly not unrealistic. I have some supercapacitors with a capacitance of 3.5kF and a rated voltage of 2.7 volts. This is almost 13kJ. They weigh a bit under 700 grams each. While this is still a bit behind the energy density of alkaline batteries, we are certainly on the right track. These capacitors are not new either, so the newest offerings in this area are certainly better than the ones I have.
Registered Member #2038
Joined: Fri Mar 20 2009, 03:39PM
Location: Bristol Uk
Posts: 60
Well i cant see that the capacitors i have will be of any use as batteries, and i dont have any intentions of trying it out either. anyone got any other serious suggestions as to what i can use these caps for?
So far we have had: DRSSTC - probably too tricky for me to take on at this stage since i am new to TC's, HV and have a rather limited knowledge of electronics in general, also i dont own a O'scope or signal generator.
SSTC - I'm quite keen to try one of these out, it would fit my original criteria of how i wanted to make my first TC (small and powered by low voltage)
I would like to try out an audio modulated TC at some point, any advice, usefull websites i should see?
What about a Marxx generator? would these caps be suitable?
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Ryan, you could use two of these capacitors in parallel (x2) for a halfbridge, and 4 in parallel (x1) for a fullbridge. these would surely never die :D.
And twist2b, i am not being lazy. Why would i research if i do not think it is practical? Even if a capacitor IS made to store as much energy as a similar size/weight battery, why would they use it more than batteries? Sure, they last longer and would have overall better performance, but in everyday use, there is not much of a point. It would be more expensive to manufacture. These would indeed be great for things that require a specialized power source or something extremely reliable, like something for the military or something else important. But for things like regular flashlights and toys and that sort of stuff, unless they can be manufactured cheaply, seems impractical.
That guy on the link SAID they should be as cost-efficient, but he does not know that. Only time will tell.
Registered Member #575
Joined: Sun Mar 11 2007, 04:00AM
Location: Norway
Posts: 263
Ryan Parle, I would follow Steve Ward design ( 4 or 6 capacitors in parallel and series configuration (0.6 or 0.99µF) with two MOSFET's to form a half-bridge would do.
Registered Member #1530
Joined: Tue Jun 10 2008, 03:34PM
Location:
Posts: 32
101111 wrote ...
Ryan Parle, I would follow Steve Ward design ( 4 or 6 capacitors in parallel and series configuration (0.6 or 0.99µF) with two MOSFET's to form a half-bridge would do.
I think that would prove to be a very satisfactory SSTC.
I recommend also winding a secondary - taking a look at how much you have done, then winding more. Try to get a nice low frequency for your coil. Mine being around 250kHz was a bit fussy to manual tune.
I know nothing about feedback tuning, maybe higher frequencies are not so bad, but your FETs might like it slow.
Ryan, you could use two of these capacitors in parallel (x2) for a halfbridge, and 4 in parallel (x1) for a fullbridge. these would surely never die :D.
And twist2b, i am not being lazy. Why would i research if i do not think it is practical? Even if a capacitor IS made to store as much energy as a similar size/weight battery, why would they use it more than batteries? Sure, they last longer and would have overall better performance, but in everyday use, there is not much of a point. It would be more expensive to manufacture. These would indeed be great for things that require a specialized power source or something extremely reliable, like something for the military or something else important. But for things like regular flashlights and toys and that sort of stuff, unless they can be manufactured cheaply, seems impractical.
That guy on the link SAID they should be as cost-efficient, but he does not know that. Only time will tell.
Eh, I think I was just a little irked... I disagree though, it uses VERY eco friendly materials, it lasts for longer periods of time (FULL lifetime) and charges close to instantly, instead of hours. Why would that NOT be worth spending the little extra cash over? Consumers WANT instant battery re-charge, and IMO are willing to pay it.
It would be awesome for cell-phones... some smart phones DON'T last all day, and to be able to just charge it up really quick-like would be a nice advantage.
Even FURTHER down, modern cars could really use it.
Registered Member #1497
Joined: Thu May 22 2008, 05:24AM
Location: Toronto, Ontario, Canada
Posts: 801
Just to weigh in, capacitors that use spiral wound plates don't have nearly the same energy density as new supercapacitors which use a carbon aerogel to provide a insanely greater surface area. Yay science.
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WOO!! just received a free bag of 942's... What to do with them?
