Excellent write-up.
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Excellent write-up.
ROFLMAOQuote:
Originally Posted by Yendor
Many people miss that phrase... it gets drowned out by shouts of "Quick, get a Camera"
This is a simplified graph of the three phase output of the alternator before both the main rectifying diodes and the diode trio. The windings and the rotor poles poles are positioned so that there is 120 degrees between each phase.
This is a simplifed graph of the output from the diode trio. There is no return path for the negative half of the wave. This is used as the rotor poles don't need a real high current and is cheap to manufacture.
The slip rings allow a DC current to flow through the rotor and produce constant north and south poles. As the rotor turns its north and south poles cut each winding at different intervals thus producing the alternating output. AC.
This is a simplified graph of the output of the alternator after the main rectifier. Note that the only path for the negative half of the waves is via the diodes so it becomes a positive voltage. The voltage you will actually see on an oscilloscope is a positive DC voltage with twice as many peaks or humps as the half wave rectifier. This configuration ensures there is maximum current output from each winding.
All for a good cause. I just stopped asking questions.......... for now. :thumbup: :DQuote:
Originally Posted by Yendor
Thanx for the two diagrams mate. That alone explains everything perfectly.
Now, I can work on my "grand design" of a redundancy for the alternator warning lamp, so when or if the warning lamp cooks itself,
field coil would still get the tiny 1.5v to get the alternator going. ;) :D
Cheers
Dom
You could always install an LED or a lower wattage globe and a ceramic resister of the right resistance and wattage in parallel. That way if the LED or lamp blows blows you will still have probably at least .75 volts available to kick start the system. Maybe just saying. It would take a while to get the combination of components right.
Yeah, it also kinda shows that the pulsed DC output that is produced by the bridge rectifier arrangement of three phase is smoother than the single phase bridge rectification.Quote:
Originally Posted by mudnut
Yeah, I reckon I can measure the resistance of the warning lamp and do some calculations with the ohms law to approximate the right resistance of the parallel resistor & the LED/globe wattage.Quote:
Originally Posted by mudnut
Cheers
Or you could just replace the bulb if it ever blows....Quote:
Originally Posted by dom14
Not hard to change a globe on a GQ.
I think an LED might be too sensitive and would glow at the drop of a hat and would get you wondering whats up.
A globe can have a fair bit of current flowing through it before it glows, and its resistance actually changes in proportion with the heat produced as more voltage is applied. That would have to be taken into account too.
I would like to the whack the probes of my scopemeter across the brushes of a working alternator. It would be interesting to watch the voltages change with the load.
Not without a possible injury. ;)Quote:
Originally Posted by mudnut
What kinda scope have you got?
Do you have a link or something that I can see?
BTW, I just tried to imagine how much that I've learnt in a few days about the automotive charging system.
I almost feel "enlightened". :D
Imagine what would happen if I have the experience and the level of understanding you blokes have!!! ;) :D:cheers:
BTW, it's great you have a scope. The stuff you can do with that would be endless.
That would be the only way to see exactly what is happening. A voltmeter would be way to slow at reading the values and only give an average reading.Quote:
Originally Posted by mudnut
I have an Allsun scope which I bought from china. It looked a bit more rugged and repairable than the first one I bought. I accidentally spiked the first one and found it was all plastic welded and impossible to fix. It turned out I was right about the Allsun as the on/off switch was jiggered within a month. I used a switch off of a Sony walkman to fix it. Using the allsun is like using a pitchfork to eat spaghetti it is so agricultural. Wouldn't touch any of their products with a barge pole.
Ok, cool. If I've got the message, you're telling me to stay away from the brand you have??!!Quote:
Originally Posted by mudnut
Is this the one?
http://www.all-sun.com/en/d.aspx?pht=1184
Having just ripped the dash out of the Excel I will be looking to fit an alternator light (& oil pressure light) on the starter box.
The Excel project is a speedway car for my 10 year old boy.
Graham
Yup, Dom. Only get one If you are prepared to take the unit apart, strip the guts of both the on/off and ac/dc butto, then solder two similar style but heavier duty switches in parrallel to the pc board. It is unfortunate that they skimped on such vital components. I only did the one switch where as in hindsight I shoulda done both.
I also got a small shock from the multimeter leads while checking a 240v circuit with the scope probe. So they have to be removed when the scope is used.
By small shock, you mean you didn't get the full 240V shock which has the potential to kill you?!Quote:
Originally Posted by mudnut
I've had a quick read through this, and am happy to say it is all well above my head and I understood next to none of it.
One thing I didn't see mentioned though, and perhaps I missed it, but is there any difference between different alternators in the way they excite and regulate and the circuitry needed? I only ask because I believe Dom has upgraded to a 110/120amp EF Falcon alternator, and I'm not sure if it's been taken into account (or if it needs to be, or makes no difference perhaps). If it's been taken into account already or doesn't matter and I've missed it, my apologies.
Yes it covers Dom upgrades. It basically covers the older style alternators with the two small wire connections "S" and "L". They all work in a similar way just what and how is done inside the regulator is different between manufactures. For example some switch positive to the field coils and other switch negative.Quote:
Originally Posted by Throbbinhood
The later model alternators that are fitted to the Y62 and Navara's are different as they are also controlled by the engine computer.
"Smart alternators" they call them, don't they? I reckon it's actually the ECU that does smart controlling. :)Quote:
Originally Posted by Yendor
I really should've removed the leads anyway. The shock was via the 1 Megohm input resistor. The initial open circuit voltage was the full 240v. Since I closed the loop, it dropped rapidly so was non-lethal.Quote:
Originally Posted by dom14
Compare that with my experience with mains electricity. I've been electrocuted countless times, lethal and non lethal, since I was a child and at least three times it was the brink of death experience. First time I managed to touch the live and neutral wires which kept cooking into my palm while I was trying to break free(don't ask what I was doing with open main electrical wires. :) ). Luckily the plug came out of the wall socket and I had a wire embedded in my palm. Second time from a TV. Third time from an old fluorescent desk lamp. That was few years back with a faulty lamp. I had hole burnt all the way into the bone on my middle finger. I was able to break free from the lamp by shoving my leg in between and pushing the lamp away.All those three lethal times the electricity managed to pass through the heart without stopping it.(But, must have bypassed the heart due to some luck). Those kid days are over and now I'm super careful. Especially, I'm super careful about poking my hands into the running engine. :)Quote:
Originally Posted by mudnut
And of course, I don't poke my hands into live electrical wires no more either.
Hehehe, I know what you mean but... Lucky your a Hindu, others only get one shot of lethal electrocutionQuote:
Originally Posted by dom14
It's not lethal if it doesn't kill ya!
And no one living has ever been electrocuted
>>>tappin from tassie
Well......it was lethal. I went to the other side and came back. ;) :DQuote:
Originally Posted by taslucas
It would've been lethal, if that was you. I got some kinda "lucky" resistance to electricity. ;)
I didn't know I am hindu Where's my turban?!! ;) :DQuote:
Originally Posted by the evil twin
If your not Hindu, you couldn't get reincarnated.Quote:
Originally Posted by dom14
If you didn't get reincarnated your dead.
If you were dead and now your not then "Welcome back and I'm really sorry about all those Jesus Jokes but can you do anything about all them peados in the black robes?"... Hehehehe
Hmmmmm....... I'll talk to cardinal Pell and get back to ya on that. ;) :DQuote:
Originally Posted by the evil twin
Gday had a search and found this did all of above. The back of my alternator is reading 11.6 when running. When car is not running but ignition on both wires on plug on back of alternator. (Red and white ) and other are reading 12 volts (or whatever battery is currently reading. Does this make any sense to anyone. Cheers in advance
Something is stuffed. Is the light on before starting the vehicle and does it turn off when running?