Where does my 12 volt resistor go?

My TSC manual doesn't show it, I just found an online wiring diagram that shows it between the terminal block and the coil and on my tractor at the moment it is between the coil and the distributor. :?

It should be just before the coil, unless your coil is internally resisted. If the coil says 12v or internal resister leave it like it is. If you can't find any writing on the coil at all put the resister before the coil, it won't hurt an internal resist coil to have the resister before the coil but if you don't have an internal resist coil and you put it after the coil it will burn up the coil.

Actually it can go anywhere in the primry ignition circuit, but it"s usally found between the key switch and the coil.

Okay, I just replaced my coil as I'm rewiring this 641 workmaster.

Even if the old coil had an internal resistor, for what reason would you wire an external resistor between the coil and the distributor???

There are two types of coil used on conventional tractor systems. a coil with about 1.8 to 2.5 ohms of resistance, and ones that have 3.5 to maybe 4 ohms. The first are called 6 volt, or 12 volt for use with an external resistor. The second group are 12 volt coils. none have internal resistors, they are just coils of wire. The coil you choose is important to avoid burning up the points and coil, or not starting.
On the FarmallIH forum there is a greaat article from John T (an electrical engineer) on the facts. It is on the first or second page called 6 and 12 Volt Coils 101 - John T. Jim

Seems to me that we have a series circuit here. Battery terminal, switch, coil of wire, resistive element to limit dc current flow during coil initialization to protect the points from excessive pitting, points with condenser across them for the same reason and noise reduction, and a battery terminal.

Since current movement is the name of the game, the current is common throughout the circuit because there is one common wire which carries all of it.....except for the point-condenser interaction.

Seems to me it is more of a convenience in the design as to what is located where, and in the case of a 12v coil whether or not an external resistor is required. If my memory serves me correctly the 12v coil is just a 6v with an internal resistor; whatever it takes to limit the current to 2-4 amperes or whatever is the magic number to get the right energy in the circuit and not burn up the points.

The purpose of the whole circuit is to fill up the coil with the correct amount of energy required to fire a dirty, worn gapped, plug. As I recall it takes about 0.15 joules (watt-seconds). That energy is derived from energy stored in the coil during the charge cycle (points closed) through the relationship w =1/2 L(i squared). L being the inductance of the primary coil winding and "i" the value of the current through it at the second the points open. Then it's just a matter of setting the desired turns ratio for the secondary voltage desired at the plug.

This is the way I see it works.

Mark

That's where mine is. Never any problems.

For electrical purposes, anywhere in the line between the key & the distributor. It is a series circuit, so it makes no difference whether the resister or the coil comes first.
As a matter of practice, in the auto trade, 12 volt with point ignition,it was placed before the coil. This was to allow the resister to be bypassed & shoot a hotter spark for starting, somewhat making up for the starter drawing down the battery voltage. When people started doing 6 to 12 conversion, they just followed this practice.
Willie

i'm cornfused,..one says there's no such thing as an internal resisted coil and everyone else talks about internal resisted coils,....who's right here ?????????

No such beasty as an internal resister. It's just a term intended
to comvey the concept an that external resistor is not required.
A 12v coil just has twice as many turns on the primary than a
6V coil.

I have 50 years experience, as does John T. I teach Electrical systems and Transportation/Power Technology at a University. John T is an Electrical Engineer. I also think Buickanddeer is an Electrical Engineer. (others on here are also experienced, those who think there are resistors inside coils just have not disassembled one to see what makes it go. We are clearly denying the existence of internally resisted 12v coils. Some company could make one, but the heat would need to be dissipated in some way, not convenient. Why build a device for 120 volt operation and run it on 220 by putting a resistor inside. The ballast resistor idea is specifically for allowing a bypass to place higher voltage on the coil when cranking. 10 volts or so due to the load of the starter motor current draw. This provides starting capability in cold weather, and more reliability. Jim

With insignificant/minor quibbles, I agree with all prior posts except Dwayne's which is wrong.

best thing i ever did was go to my local napa and tell em i wanted a true 12 volt coil for my '62 Ford 2000...tractor has never run better.

(quoted from post at 16:37:24 03/11/12) best thing i ever did was go to my local napa and tell em i wanted a true 12 volt coil for my '62 Ford 2000...tractor has never run better.

Click to expand...

I went to my Napa dealer and told him I have a 1958 Ford Workmaster and I want the best coil you got. $42 later I had a coil.


Guys, I appreciate the help. I got frustrated yesterday with all the spliced wires, safety start button was by passed, old alt. that was cobbled in and burnt terminal block. Well... I'm starting over!


I don't want offend anyone here but I'm planning on following this wiring diagram from another fella's web site. I'm adding a voltmeter and about to head to radio shack for some diodes.

The second one down. It's for an older tractor, but looks like what I'm p to. I added a 10si yesterday as well.

http://www.myfordtractors.com/12volt06.shtml


I'm sure I'll have more questions here in a bit.

I distinctly remember, somewhere in the distant past, coming across coils with internal resistors, not wiring resistance, and I never could figure how someone would put a dissipating element in a closed container of oil. Didn't make sense to me, nor mounting the coils to the side of the engine block.

Mark

See the URL for the answer IN MY OPINION AT LEAST FWIW

John T
Betcha theres NO Resistor inside the coil

Id put the ballast resistor after the Ign switch before and ahead of the coil primary input NOT between coil primary output and points.

John T
Coils 101

I distinctly remember, somewhere in the distant past, coming across coils with internal resistors, not wiring resistance, and I never could figure how someone would put a dissipating element in a closed container of oil. Didn't make sense to me, nor mounting the coils to the side of the engine block.

Mark