Farmall b rectifier

JRHall · Feb 4, 2019

Finally got new starter and saddle switch on my B and got it running. Set up from previous owner was a push button near steering wheel that rectifier wire and starter cable attached to with 12V hot from battery on other side of switch. Now that I?m using a saddle switch on starter does the rectifier wire to the cable side of that switch?

Bob · Feb 4, 2019

Are you using momentary contact pushbutton switch to "excite" the alternator, and have a diode in that circuit?

If so, I think you have it figured out.

Or???

Janicholson · Feb 4, 2019

A push button (or oil pressure switch) is all that is needed in the alternator excite circuit. From the non grounded side of the battery, or the cable attached to the saddle switch, run a 14 gauge wire to a push button (momentary on) and then to the alternator #1 terminal (assumes a Delco 10SI alternator, or a Hitachi at the L terminal) there is no need for a diode. If an oil pressure switch is used it needs to be a 2 terminal with 5 psi on (NAPA) I also assume your tractor has a mag. Jim

JRHall · Feb 4, 2019

The way the previous owner had it wired with 12v conversion was hot from battery into a push button by steering wheel with other side of switch going to starter and rectifier on side of alternator. The starter was bad and new starter I bought has a contact plate for a saddle switch instead of a post so I bought a saddle switch that mounts on starter. Tractor starts now and runs well but if I add rectifier wire to that switch it?ll be continuously hot. So I?m assuming I?ll need yet another switch for alternator rectifier?

Bob · Feb 4, 2019

(quoted from post at 16:50:47 02/04/19) The way the previous owner had it wired with 12v conversion was hot from battery into a push button by steering wheel with other side of switch going to starter and rectifier on side of alternator. The starter was bad and new starter I bought has a contact plate for a saddle switch instead of a post so I bought a saddle switch that mounts on starter. Tractor starts now and runs well but if I add rectifier wire to that switch it?ll be continuously hot. So I?m assuming I?ll need yet another switch for alternator rectifier?

Can you post a photo of what you have and what you are calling a rectifier?

If this is a Delco "10SI-style" alternator, and you want to use a momentary pushbutton switch to "excite" the alternator after startup, you do not not a diode (if that's what you are calling a rectifier).

You need a wire from the alternator's #1 terminal to one side of the momentary switch, the other needs battery power.

And also a wire from the alternator's #2 terminal to the alternator's large output stud, along with the wire that carries charging current.

BarnyardEngineering · Feb 5, 2019

Yes, a "rectifier" is a set of diodes used to convert AC into rough DC. Totally unnecessary on a Farmall B, as there is no AC voltage.

Yes, if you connect the wire to the saddle switch post, it will be hot. So yes you will need a switch, but why "another" switch? Can't you just use the existing switch?

Farmall b rectifier

JRHall

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Bob

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Janicholson

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JRHall

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Bob

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BarnyardEngineering

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