Alternator Warning Lamp Circuit Question

[mudnut]

Excellent write-up.

[the evil twin]

Haven't you heard the phrase "hold my beer and watch this" nothing bad has ever followed

ROFLMAO

Many people miss that phrase... it gets drowned out by shouts of "Quick, get a Camera"

[mudnut]

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.

[mudnut]

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.

[mudnut]

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.

[dom14]

Nah my head hurts when I do this lol

All for a good cause. I just stopped asking questions.......... for now.

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.

Cheers
Dom

[mudnut]

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.

[dom14]

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.

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.

[dom14]

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, 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.

Cheers

[Yendor]

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.

Cheers

Or you could just replace the bulb if it ever blows....