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Forum Index : Windmills : 3 phase rectifier - confused
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goingbroke Newbie  Joined: 29/05/2012 Location: United StatesPosts: 21 |
Hi all…. OK here is another stupid question from a newbie. While checking the DC output on the project I am helping my Grandson with, my meter was set to check AC. Here is my stupid question, if these are designed to convert AC to DC why does it still show AC voltage…… 
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| VK4AYQ Guru  Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Goingbroke If the rectifier is not connected to a DC load such as a battery there will be a residual AV voltage across the output of the rectifier it is the ripple effect of diode rectification, on a CRO you can actually see it as a series of 3 chopped AC voltages, when the load is applied these chopped voltages are what is then DC, that is why a rectifier circuit on electronics have a C-L-C circuit to smooth this effect out to give a more pure DC voltage. C L C circuit is a Capacitor L is an induct or And C is a capacitor again. Hope that helps All the best Bob Foolin Around |
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| goingbroke Newbie Joined: 29/05/2012 Location: United StatesPosts: 21 |
Hi Bob, Thank You for the information. Very well explained, is this type of circuit worth investigating or is it best to leave well enough alone. Thank You again….. Allen 
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Allen It really depends on what you are doing with the DC if it is just to charge batteries it is not important to have a C-L-C Filter but if you are running audio or other electronic equipment of the DC it can be useful as it makes the equipment more stable and in the case of Audio it gets rid of some of the hum that would be audible. All the best Bob Foolin Around |
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| electrondady1 Senior Member  Joined: 12/02/2009 Location: CanadaPosts: 208 |
what about if i'm using the rectified ac in a hydrogen cell? |
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| goingbroke Newbie Joined: 29/05/2012 Location: United StatesPosts: 21 |
Hi Bob. Thank You for every thing. I am just going to charge batteries. So if it ain't broke don't fix it... Allen  |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Electrodady In my experience a HHO cell works better with a pulsating DC than a smooth DC I would suggest you feed into a switch-mode motor controller to control the amps and the higher frequency switching gives a better HHO conversion. http://www.ebay.com.au/itm/181401997684?ssPageName=STRK:MEWA X:IT&_trksid=p3984.m1438.l2649 Link to ebay for the one I use:- http://www.ebay.com.au/itm/181401997684?ssPageName=STRK:MEWA X:IT&_trksid=p3984.m1438.l2649 All the best Bob Foolin Around |
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| electrondady1 Senior Member Joined: 12/02/2009 Location: CanadaPosts: 208 |
i was mostly concerned with the ripple contaminating the gases creating a dangerous condition. not sure if it can help me or not . I'm quite bad at electronic circuits actually, it somehow uses pwm. it creates a high frequency pulsed dc. and can control the voltage to dc motors. i am rectifying a couple of mills separately and then combining the outputs there is absolutely no controls on the devise. i have been letting the voltage float. but it's very low amperage. rectified the alternators give 14 DC volts @60 rpm. at that speed into a battery they only push a few amps as it stands now the cell is holding the voltage and mill speed down quite a bit . i was thinking of putting a capacitor between the mill and the cell to see how that would affect the rpm. the windy season is just getting started around here, I'm about 1klm. back from the beach you can hear the wind and water tonight i'm not saving the gasses at this stage just letting them dissipate. |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Electrondady There will be no problem with contamination of the gasses it is just that the process you are using is less efficient than a high frequency pulse mode supply, but if you are just letting the gas dissipate then no problem, it does seem a shame to not use the energy you are harvesting for something useful. The capacitor you mention will not make any appreciable difference unless you get a multi farad supercap. You could burn the gas in a heater and get a bit of warmth as I believe you need some at the moment with the talk of a new ice age coming. All the best Bob Foolin Around |
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| electrondady1 Senior Member Joined: 12/02/2009 Location: CanadaPosts: 208 |
there is a new ice age in Canada every year! last Friday was the first snow fall in my town. we received 30-40cm. in 18 hrs. that's a whack of snow. pulse width modulation has proven useful directly on windmill output. there are four terminals on the devise is that two wires in and two wires out? can i put low tech. dc in and get hi tech dc out? i have a wood stove in my shop i could use both gases in there. . |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
The device takes a DC power source and then turns the output into a PWM voltage less than the input voltage thereby controlling the current so you could say uncontrolled DC in and controlled DC out in a high frequency PWM mode. Be careful about using the gas as you could put your man cave into orbit you included if you let the gas into the atmosphere in your workshop with the fire going, normally you would have a flash protector after your cell to prevent flash back. A good storage medium is a inner tube out of a truck or tractor then another flash protector before going to the burner or whatever. Be careful as there is a lot of bang in Browns Gas. All the best Bob Foolin Around |
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| electrondady1 Senior Member Joined: 12/02/2009 Location: CanadaPosts: 208 |
i had a little cell blow up on me back when i was 11 years old not much of a dare devil with the hydrogen now . it does load the mill in an interesting low speed kind of way. |
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