Anyone know why a single 330uf cap doesn't work in this setup yet two series-pairs in parallel does ? :
Part 1 : http://www.youtube.com/user/tvryb#p/u/14/sjtwZwBaprc
Part 2 : http://www.youtube.com/user/tvryb#p/u/15/49iwl-GsYaA
Thanks,
Gary.
When the capacitors are in series they change their values. The value now is 1/? + 1/? of the originals.
Mixing them you got the correct value that was needed.
Jesus
That's true but ... what he wanted was a 330uf cap, what he did was put two series-pairs in parallel and achieved the same effect as a 330uf cap.
My question is :
Why doesn't a single 330uf cap work but 4 caps pretending to be a single one do work ?
Gary.
Do you mean, like this?
Yes hes using four 330uf caps to get 330uf.
Apparently one 330uf on it's own doesn't have the same effect.
Gary.
It's how you double the effective working voltage rating. Say you have one 330 uF cap with a rating of 200 V, but your circuit might be making spikes above that voltage and you don't want to puncture your dielectric. So you put two caps in series: This doubles the working voltage but, of course, halves the total capacitance. So you put two series strings in parallel, as in the circuit diagram above. 4 identical caps, series-parallel == the same capacitance but at twice the working voltage...so the arrangement can hold 4 times the energy of a single 330 uF cap without fear of puncture. Energy on a cap goes as the square of voltage: E= (CV^2)/2
It's a common technique: stacking caps in various ways to fulfill a voltage and or capacitance requirement. With good quality, identical, capacitors it usually works out well...if you have the physical room. Of course, a single cap of the correct rating and type would probably have lower overall losses and ESR and self-inductance than a bank of sub-capacitors, and this might be important to a particular design. But series-parallel cap banks are capable of great tricks: See Marx Bank for example.
All he is doing is using capacitors as NON HEATING resistors to drop the wall voltage down to what he wants.
Xc = 1/2 Pi F C (Reciprocal of 6.28 x Freq x Capacitance)
The Caps MUST BE AC Rated, like Microwave Oven Caps, Electric Motor Caps, etc. Electric Motor Caps might be best because they have the highest capacitance.
So he just connects different caps in series & parallel to get the right impedance, which gives him the right voltage at his fuell cell.
In fact, WHY EVEN USE A RECTIFIER? H2O Cells work GREAT on AC too.
VERY CLEVER IDEA!! Because the circuit presents a capacitive reactance, his home Electric Meter is probably reading less than he is really using!!!
CAUTION: This type of circuit can present a Dangerous Shock Hazard because there isn't any Isolation from the Wall Voltage. BE CAREFUL!
.
You are using these capacitor networks in an A.C. application.
You have three options:
1. Wear protective goggles when power is applied.
2. Connect the series strings of capacitors so the polarities oppose. i.e., connect the negative poles together and use the positive poles for ALL other connections. Plus, follow rule #1.
3. Toss a coin. Without understanding how these things actually work it may work for a while without exploding. It may not.
The only electrolytic capacitors designed for use in A.C. circuits, without exploding, either use design that prevents the erosion of the dielectric during reverse polarity charges -or- is actually two, or multiples of two, electrolytic capacitors in one can connect as in #2 above.
Be safe.
BTW: If you use the series circuit to step voltage down, it isn't a Capacitor Transformer. It is a Capacitive Voltage Divider and an excellent tool under common use.
Thanks Tinsel, FB and BEP :)
BTW, i'm not using it from the wall, i'm using it to stepdown output from my little induction generator, which is putting out 200-250V at about .030 amps.
Thanks again for help,
Gary.
Heh...BEP is totally right, I didn't even consider that someone might use a polarized electrolytic capacitor in this kind of application. For AC from the wall you would definitely want to use oil-paper types, the big cans with no polarity markings. The photo above appears to show some polarized electrolytics (the small bundle)....be very careful.
Speaking as one who has blown up many capacitors over the years, I can tell you that even a small electrolytic can explode violently when given a strong reverse pulse. The can flies off like a bullet and the foil inside unrolls like a party favor, and if your eyeball happens to be in the way....ouch.
I try to select cap working voltages at least twice the anticipated peak circuit voltage. Depending on the total capacity, a puncture can be serious, or not so much. That is, if you short-circuit 30 mA at 220 V, (no capacitance) that's no big deal. But if a single 100 uF cap in a 10,000 uF parallel bank shorts while the bank is charged to 220 V with that same power supply... stand well back.
OK i'm going with a single 1.05uf 2100VAC cap to replace his 100uf cap :
http://qvision.pwp.blueyonder.co.uk/cap.jpg
To replace his four 330uf caps i'm using one 35uf cap at 450V (electrolytic).
But i'm not sure about the connections in the oil cap, i think it may be two caps in one container but i can't find specs or pinouts.
Anyone know how the one in my picture is connected internally ?
Thanks,
Gary.
It is just 1 cap in 1 container rated at 1 uF.
However, you might need more microfareds to get enough voltage.
You are right, it is good practice to just start small & work your way up.
.
Thanks FB.
Why does it have 2 pairs of terminals if it's one cap ?
Looking from above the polarity is like this :
- -
+ +
But they short out unless you connect them diagonally, which is why i thought it may be two caps.
Thanks,
Gary.
It's one cap. You should be able to see that the two spadelug terminals inside each black cylinder are in fact physically connected. The polarity markings and the multiple spade lugs are there so that the cap can be inserted into the microwave oven and hooked up to the correct wires easily and quickly.
These caps are not "polarized" in the same sense as electrolytic caps, so you don't have to worry about that. There will usually be some kind of marking to differentiate the outside/inside electrodes in the rolled-up paper/foil inside the can; this can be a small mark, like a dot or triangle, near one of the terminals or can be indicated by a different color (black vs. brown for example) of the terminal insulators.
Even a 1 uF cap charged to a measly 12 volts can create a damaging arc.
Please be careful.
It's a good idea to store "big" caps with a shorting wire across the terminals; this one won't be dangerous but truly large caps can "self-charge" from static in the environment and give you quite a shock unless they are shorted in storage.
Also, please remember that the energy on a cap goes as the square of the voltage. If you charge that cap to 24 volts it will have 4 times the energy it has at 12 volts. When you start getting up into the kiloVolt range, that little 1 uF capacitor can be deadly.
Thanks again Tinsel, that explains a lot.
I'll be very careful :)
Gary.
Quote from: DeepCut on November 24, 2010, 11:33:11 AM
Yes hes using four 330uf caps to get 330uf.
Apparently one 330uf on it's own doesn't have the same effect.
Gary.
I've been thinking about that. What
"doesn't have the same effect", assuming the combined parts are all the same value and only the voltage tolerance is doubled on the multi-unit setup?
--Lee
Quote from: FatBird on November 25, 2010, 09:25:28 AM
In fact, WHY EVEN USE A RECTIFIER? H2O Cells work GREAT on AC too.
The reason a rectifier is used, is to keep the hydrogen and oxygen produced separately at each electrode. With AC, you get both gases present at both electrodes. The resulting mixture of hydrogen and oxygen (sometimes called Brown's gas) is much more dangerous (explosive) than when the gases are kept separate.
The results can be tragic.
http://pesn.com/2010/06/18/9501662_water-fuel-research_Explosion_kills_inventor/
A guy said to connect electrolyte caps in series with same polarity together for step down. Can one post a diagram to see exactly how?
Thanks