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very basic help required please.

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aljaxon

New Member
but if i am after the rectifier at the battery isnt that 12v dc?
if the alternator spikes will the rectifier stabilise it to just 12 volts or will it pass on the spike but in dc?
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
"rectifier" doesn't make any sense in your sentence.

The sentences make sense if you use the word "regulator".

i.e.
quote modified in bold said:
but if i am after the regulator at the battery isnt that 12v dc?
if the alternator spikes will the regulator stabilise it to just 12 volts or will it pass on the spike but in dc?

I'm assuming a car, so I can talk about it. The alternator is 3-phase. Each phase is rectified and the battery acts as a filter. Regulation is accomplished by turning on and off the rotor current. The battery acts as a filter, but not a good one.

There is 3-phase AC present at likely less than 100 mV p-p. That's known as ripple. You turn a headlight on, you generate noise. You turn a fan on, the alternator coil turns off, you generate noise within the electrical system.

The radio and ECM use stabilized voltages such as 5V DC which are derived from the 12 V electrical system. Even though the system is "12 V", the nominal voltage is abut 13.8 V.
 
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aljaxon

New Member
rectifier it might well be, all i am saying is at the battery i shouldnt be getting minus volts should i? are minus volts only in ac currents?

its a motorbike and i'm pretty sure its 12 v dc.
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
Here https://patrickmsblog.blogspot.com/2010/11/ws3-ocilloscope-patterns.html is pic of alternator ripple" The frequency changes with engine RPM. So, in theory it's DC with ripple on it. There can be Large spikes in the negative direction and large spikes in the positive direction. These "spikes" are of very short duration.

In some cases if the wrong diode is used, they can get through. A Peak reverse voltage of 200 to 400 V would be appropriate,

Remember to that the system should be tolerant of electrical failures as well. Failure to charge and overcharging are common failure modes.
 

throbscottle

Well-Known Member
Aljaxon - did you get the data you needed from the circuit? Reading all the discussion on alternator outputs and ripple has made me fascinated!
 

aljaxon

New Member
not as yet. my sticking point is how to get the gsf dyno software to accept my wav files. its very fussy.
i am going to have to try to input the "sound" from the voltage divider to my camcorder. my camcorder produces files that can be converted that the gsf software likes.

i was just a bit wary of damaging any circuitry in my camcorder.

i suppose its a bit like my tv. i dont know exactly how all the circuits work but i know how to turn it on and watch it.
i now know how to make a divider to output any given voltage. the why is a bit vague but i can live with that.
i am gonna have a go tomorrow and will report my findings
thanks for all the help and pointers so far
 

aljaxon

New Member
right i have got the software to accept my wav files but the "sound" of the electronic pulses " doesnt give an impression or steady rising revs, more like rising then step down then rise then step down. so the software interprets an actual steady rise of revs as almost steady revs.
i am uploading it to youtube for those concerned who may help me although it is getting a bit off topic of this forum.
cheers
 

alec_t

Well-Known Member
Most Helpful Member
Can you post a wav file for other members to check?
 

aljaxon

New Member
i uploaded it to youtune here

and made a rar out of the wav and attached it
 
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aljaxon

New Member
update, i returned the divider back to its original spec with the 33 ohm resistor and connected it onto the battery and the same thing happens, as the tone rises it steps down in key every 2 seconds as it rises so its as if im changing gear going up and down. as opposed to a simple rise of revs.
i fastened it to the ac side (upstream of the rectifier) and bingo. a steady rise in tone. and the software accepted the wav i produced so i'm sorted.
thanks to all the help on here.
 

dr pepper

Well-Known Member
Most Helpful Member
Sounds like the o/p wants to record alternator ripple to be converted into an rpm file via audio processing.
Beware this will be specific to your bike engine, different bikes might have a different number of poles in the alty and different alty gear ratio's.
It is never the less a good non invasive way to pick up rpm's, diesels often use the alty to drive the tacho, allthough theres usually a direct tapping - 'w' terminal.
 

aljaxon

New Member
yes i suspect it will be specific to my engine but as long as it is constant and accurate enough for me to modify stuff like ignition timing advance and see the improvements in rpm plotted on graphs against time or power/torque then it will be fine.
 

More Coffee

Member
Im probably going to get laughed at:p

But shouldnt there be a capacitor there..Im mean it should smooth out the ripple and stepping..
Also,did you try it on a battery that needs so charging or a fully charged battery ,,my mundane thinking is that the stepping may be the regulator sampling the battery voltage ,cutting in and out as it were ,as the rev's go up the stepping is more regular as the battery no longer needs the current cuz its "full",or at least bumped up and then it settles back,like when you shut the engine off and the battery voltage goes from 13.8 back to 12.8 or 12.6..theres always a little ebb and flow in the charging circuit.The alternator wants to maintain a constant in the battery while the demand of the running engine system applies load..
Just for kicks ,,record your sound while you put a load on the battery ,like a couple of head lights or something.

just throwing it out there:eek:
 
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dr pepper

Well-Known Member
Most Helpful Member
Sounds right to me more coffee.
However there is probably a cap on the input of the recorder, it wouldnt be bad practice to include one though.
And with more load on the electrical system there probably will be more ripple making the recording 'louder', if you plug 'phones into your recorder, start the engine then switch on headlights, brake light etc you'll hear the changes.
I'm not sure I'd want to rely on performance data provided by this method to go and change ign timing etc, you'd have to use the same piece of road in the same conditions etc to get meaningfull results.
 
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aljaxon

New Member
my divider ive been assured can only output millivolts, my laptop cant detect it but my camcorder can.
i have done probably a hundred runs on a mile long stretch of road 2 miles away from my front door and only sample third gear and can cut out a sample from exactly 3000 to 8000 or whatever. i was using a mic fastened to the airfilter and that was pretty accurate but the designer of the software said for best results use a feed from alternator.
someone else said you can get the same info from the battery. but you can hear the stepping which renders it useless.
the alternator feed is perfect.

my secluded test road as long as it isnt too windy the whole process is that accurate i can tell on the graphs which direction i was going cos its ever so slightly uphill.
i have a zeeltronics programmable ignition curve and can set my ignition curve by using 10 editable points placed anywhere over the rev range. at the roadside using a handheld programmer (strapped to my tank!!!) it can store 10 different curves and i can input them to the cdi thingy and even edit the curve but only while the engine is off.

i have learned loads on ignition timing stuff that i havent read anywhere on the net. stuff that at first had me scratching my head.

i can apply this software to loads of mods -porting ,pipes, head skimming and reprofiling and jetting etc.
before i used to use a camcorder strapped to the bike and then using adobe premier pro to analyse and compare different runs to determing which state of tune was best.
my zx6r j1 goes over 170mph. ( for those not in the know for a 600 thats fast.)
its 12 years old and its full race pipe modded jets and shimmed needles were all painstakingly set up by trial and error and prem pro!!!
i also own an 04 zx10r -998 cc so i do know what a really fast bike goes like.
 
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