Electrical for Dummies

Can anyone recommend a resource that will describe, in detail, the difference between generators, alternators, and magnetos. The pros and cons and how to setup each system. I'm redoing an H (my first restore) which had an alternator and I'm thinking about getting back to something closer to the original. To show you how little I know about this - is it possible to setup a 12v system with a generator? Or, must all generator systems be 6v? The serial on my machine is in the vacitinity of 108000 (1942). Thanks for any references you might suggest.

A magneto is something completely different than a alternator and generator. the magneto makes the spark for the spark plug. alternators are used(I believe) to update the tractor to todays batterys and part selections. It's alot easier to find parts for a 12 volt system at a car junk yard than it is for a 6 v. I like to stick with the 6v. Theyre basically the same. Something charges something else and it all works happily. if you already have 12v it'll work fine but 6v is original. it's more to your taste. if you know where you can get a generator and know a shop thatll work on em go for it. If you do switch it switch the bulbs to 6v or theyll be dim and thats sbout all you have to switch well and get a 6v battery

I guess i didn;t really answer your question though. A magneto makes its own spark due to the rotation of the motor. Its exactly like small engines (lawn mower etc. Also alternators are much lighter than generators

Yes you can use 12 volt with a generator. A 6V generator can be rewired as 12V. IH used 12V generators from about the mid-late 50's on some models until they eventually had everything with an alternator. If you can still see the original tag on a Delco generator, 6V had a black tag, 12V, red tag.

(quoted from post at 00:39:49 10/02/10) Can anyone recommend a resource that will describe, in detail, the difference between generators, alternators, and magnetos. The pros and cons and how to setup each system. I'm redoing an H (my first restore) which had an alternator and I'm thinking about getting back to something closer to the original. To show you how little I know about this - is it possible to setup a 12v system with a generator? Or, must all generator systems be 6v? The serial on my machine is in the vacitinity of 108000 (1942). Thanks for any references you might suggest.

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David, you are a man after my heart as I spent a good part of my life teaching electricity and magnetism. I recommend that you take a night class in basic electricity which usually includes charging and starting systems. It is very hard to jump right in without some understanding of volts, amps, and ohms.

In a nut shell - A generator makes electricity and an alternator only amplifies it.

I have a set of 9 Delco Remy "Training Chart Manuals" that will give you a lot of basic information on basic electricity, i.e. use of volt/ohmmeters , Ohm's law, troubleshooting methods, generators, voltage regulators etc. They are 1960's vintage (guess that dates me, huh) that I used a lot when I taught Airframe Electricity at Spartan School of Aeronautics. Send me an e-mail if you'd like some more information on these. If you like to read and learn these would help you a lot. I might be willing to part with them!!

Not corrrect. Both a generator and an alternator make electricity!!! An AMPLIFIER amplifies electrical signals, but doesn't create them.

Seems that electrical inquiries have a tendency to bring out incorrect responses. Why is that?

A magneto makes its own fire when the magnets pass by the coil as long as the magnets have strong magnetism.. Hal

For DC generator and ignition information, take a look at the electrical manuals linked at the Rudi's Cubs side. Here' the link to the index page:

http://www.cleancomputes.com/Cub/Blue%20Ribbon%20Service%20Manuals/index.html

A generator makes D.C. electricity. An alternator is also a generator, but it makes A.C. electricity, but then, because of the diodes, that A.C. current is converted to D.C., which is required for nearly ALL automotive electrical systems.

(quoted from post at 12:40:38 10/02/10)
A generator makes D.C. electricity. An alternator is also a generator, but it makes A.C. electricity, but then, because of the diodes, that A.C. current is converted to D.C., which is required for nearly ALL automotive electrical systems.

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When alternators were first introduced DelcoRemy referred to them as AC generators.

The electricity generated in the coil windings of both DC generators and alternators is AC current. It is generated by passing a coil through a magnetic field.

In a generator the magnetic field is created by the field coils and pole shoes mounted inside the case. One pole shoe will be a magnetic North and the other a magnetic South. The coils moving through this magnetic are mounted on the armature. The ends of each coil is attached to commutator segments mounted 180 degrees apart. As the coil passes through the magnetic field one end of the coil will have a positive charge and the other end a negative charge. As the armature turns past the magnetic field of the N pole shoe and enters the magnetic field of the S pole shoe the positive and negative charges in the coil will be reversed. This means the electricity generated in the individual coils is indeed AC current. A generator rectifies this current to DC by mounting the brushes so that when the N & P charges in the coils are reversed the commutator segments now contact opposite brushes so the electrical output will always flow in the same direction.

An alternator generates the electricity by rotating the magnetic fields inside the stator coils. The rotor of the alternator has a coil in it that becomes an electrical magnet when current is passed through it. One end of the rotor will be the N pole end and the other will be the S pole end. On each end of the rotor coil is an iron shell that has fingers that intertwine with each other. One of these shells will be the N pole of the magnet and the other will be the S end. Since they are intertwined there is a magnetic field between each gap creating multiple magnetic fields around the outside of the rotor. The electricity is generated in the stator windings that are mounted in the case. Usually there are three windings in automotive alternators. (The stator windings will have their ends connected in pairs [Delta] or share a common connection on one end and individual wires on the other end [Y]). Each end of the stator windings is connected to a pair of diodes, one N and one P. The diodes rectify the AC current to DC output.

The main advantage of an alternator over a generator is that in a generator all the generated current has to pass through the brushes while in an alternator the only current passed through brushes is the field current. Generator bushes contact a segmented commutator and when current output is increased, arcing between the brush and commutator becomes a problem. Brushes in an alternator contact slip rings so they maintain a constant contact resulting in longer life that in a generator.

Thank you Owen. I would've had to dig out my books and refresh my memory before I could've said it as well as you did.

I will add to the content here (except about amplification which it does not do) with the desirability of old automotive text books. A Auto Electrical system diagnosis and repair manual (Crouse as an author, comes to mind) from the early 1960s will cover both. There are plenty of 12v Farmalls. Jim

Have you ever unwound an armature? The wire ends are not connected 180 degrees apart. They start at one bar, are wound around the armature back to the commutator segment next to the one it started from. It it one continuous loop with no beginning or end. The brushes that pick up the current are 180 degrees apart. Also a generator or alternator doesn't make electricity. What is in a magnetic field is electricity. The wires passing through that field are just harvesting it.

(quoted from post at 22:05:35 10/02/10) Have you ever unwound an armature? The wire ends are not connected 180 degrees apart. They start at one bar, are wound around the armature back to the commutator segment next to the one it started from. It it one continuous loop with no beginning or end. The brushes that pick up the current are 180 degrees apart. Also a generator or alternator doesn't make electricity. What is in a magnetic field is electricity. The wires passing through that field are just harvesting it.

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That is certainly true and it makes the armature much more efficient. The working principle however, is the same as a single wire connected 180 degrees apart. By wiring them as they are you get a gain by using multiple coils in the armature. The same applies to the stator windings in alternators. My intent was more to describe how it all works rather than getting more involved with specifics.

You could also say the electricity is already in the wires because passing them through a magnetic filed merely provides the force necessary to move the existing electrons from one atom to the next through the circuit.