Yesterday's Tractor Co. Low Prices, Parts Ship Fast!
Click Here or call 800-853-2651 
   Allis Chalmers Case Farmall IH Ford 8N,9N,2N Ford
   Ferguson John Deere Massey Ferguson Minn. Moline Oliver
 
Marketplace
Classified Ads
Photo Ads

Community
Discussion Forums
Project Journals
Tractor Town
Your Stories
Show & Pull Guide
Events Calendar
Hauling Schedule

Galleries
Tractor Photos
Implement Photos
Vintage Photos
Help Identify
Parts & Pieces
Stuck & Troubled
Vintage Ads
Community Album
Photo Ad Archives

Research & Info
Articles
Tractor Registry
Tip of the Day
Safety Cartoons
Tractor Values
Serial Numbers
Tune-Up Guide
Paint Codes
List Prices
Production Nbrs
Tune-Up Specs
Torque Values
3-Point Specs
Glossary

Miscellaneous
Tractor Games
Just For Kids
Virtual Show
Museum Guide
Memorial Page
Feedback Form

Yesterday's Tractors Facebook Page

Related Sites
Tractor Shed
TractorLinks.com
Ford 8N/9N Club
Today's Tractors
Garden Tractors
Classic Trucks
Kountry Life
Enter your email address to receive our newsletter!

subscribe
unsubscribe
  
Discussion Forum
Show Parts for Model:

Diode for alternator wiring - Which one is correct (picture)

Welcome Guest, Log in or Register
Author  [Modern View]
AL Farmall Boy

12-08-2010 09:55:08
74.248.177.194



Report to Moderator

Hey guys, I recently went to a local electrical supply warehouse and purchase some diodes for the 12 volt alternator wiring on my Farmall tractors. If I understand correctly, the diode should be 200 milliamps (or 20 amps). Below is a picture of a diode I purchased at Radio Shack several months ago that is 200 mA. Next to it is a diode I purchased at the supply warehouse that is rated at (I believe) 230 mA. They are much different in size and was wondering if they may have sold me the wrong thing, or if this is correct. The reason for the purchase at the supply warehouse is because I can get them for $0.32 each, compared to Radio Shack where they are around $3.00 each.

[Log in to Reply]   [No Email]
AL Farmall Boy

12-10-2010 21:55:12
74.248.177.80



Report to Moderator
 Re: Diode for alternator wiring - Which one is correct (p... in reply to J,D.HEICHEL, 12-08-2010 09:55:08  
Thank you. I thought so. I bought several new fuse assemblies at the local electiral supply just like the origninal ones. I got 25 amp glass fuses for them, and think they will work just fine.



[Log in to Reply]  [No Email]
cannonball

12-10-2010 05:23:29
173.185.58.21



Report to Moderator
 Re: Diode for alternator wiring - Which one is correct (p... in reply to AL Farmall Boy, 12-08-2010 09:55:08  
many years ago I used a start button, I just pushed it one time after tractor was runnung



[Log in to Reply]  [No Email]
AL Farmall Boy

12-08-2010 19:57:16
74.248.177.180



Report to Moderator
 Re: Diode for alternator wiring - Which one is correct (p... in reply to John.w, 12-08-2010 09:55:08  
Quoting Removed, click Modern View to see

Ok, 1 more clarifacation that the wiring diagram didn't explain. Does the glass fuse holder go inline betwee the ammeter and the light switch connection?? (I am using Bob M's 12 volt alternator conv. diagram)



[Log in to Reply]  [No Email]
Janicholson

12-10-2010 11:19:15
199.17.6.126



Report to Moderator
 Re: Diode for alternator wiring - Which one is correct (p... in reply to AL Farmall Boy, 12-08-2010 19:57:16  
yes.



[Log in to Reply]  [No Email]
Bob

12-08-2010 19:26:48
69.178.228.68



Report to Moderator
 Re: Diode for alternator wiring - Which one is correct (p... in reply to AL Farmall Boy, 12-08-2010 09:55:08  
For long, trouble-free life, use a diode rated WAY beyond what MAY be needed. I use 1N5408 diodes, 3 Amps, @ 1000 PIV. They cost well under a buck apiece from the right sources, so durability needn't break the bank!



[Log in to Reply]  [No Email]
AL Farmall Boy

12-08-2010 16:29:25
74.248.177.180



Report to Moderator
 Re: Diode for alternator wiring - Which one is correct (p... in reply to Docs69, 12-08-2010 09:55:08  
Quoting Removed, click Modern View to see

Thank you all for the help!!! I went to the supply house and made sure my diodes were correct, and it turns out they are 2.5 amp therefore waaayy overkill which is good.
Yes, I do too like the pilot lights because it adds a nice touch to the dash as well as serves a purpose as exciting the alternator. I generally like to use them when there is a hole already in the dash that needs to be filled. At $0.40 per diode, and around $8.00 per light; it is definitely more cost effective. That really doesn't matter though.

Question: Does the diode excite the alternator?? If not and there is no light, then what does??

[Log in to Reply]  [No Email]
John T

12-08-2010 17:42:17
66.244.97.31



Report to Moderator
 Re: Diode for alternator wiring - Which one is correct (p... in reply to AL Farmall Boy, 12-08-2010 16:29:25  
Question: Does the diode excite the alternator?? If not and there is no light, then what does??

Its actually the current that passes through the diode orrrrrrrrrr resistor orrrrrrrrrrr an idiot light that excites the alternator. If theres no circuit to supply current REGARDLESS if it has to pass through a diode or idiot light or resistor shes not gonna initially excite.

John T



[Log in to Reply]  [No Email]
Bus Driver

12-08-2010 16:05:44
66.226.40.41



Report to Moderator
 Re: Diode for alternator wiring - Which one is correct (p... in reply to AL Farmall Boy, 12-08-2010 09:55:08  
IH used a 25 ohm resistor in their earliest alternator equipped tractors. The typical indicator light has about 53 ohms resistance when the filament is hot. I use a 44 ohm 5 watt wirewound as it is a common size at the supply house.



[Log in to Reply]  [No Email]
John M

12-08-2010 14:51:59
67.231.169.173



Report to Moderator
 Re: Diode for alternator wiring - Which one is correct (p... in reply to AL Farmall Boy, 12-08-2010 09:55:08  
I gave up on trying to wire in a diose or a light. I just put a Normally Open oil pressure switch somewhere where theres oil pressure and run the wire from the alt to the switch, then to the gauge.



[Log in to Reply]  [No Email]
tempola

12-08-2010 17:17:15
75.121.249.127



Report to Moderator
 Re: Diode for alternator wiring - Which one is correct (p... in reply to John M, 12-08-2010 14:51:59  
I always replaced the ignition switch with a DPDT, to create a accessory terminal but I never thought about using an oil switch! that is very clever!

are you talking about a switch similar to the older hydraulic taillight switches on the older cars? what is the part number?

Andy



[Log in to Reply]  [No Email]
John M

12-08-2010 17:34:00
67.231.169.173



Report to Moderator
 Re: Diode for alternator wiring - Which one is correct (p... in reply to tempola, 12-08-2010 17:17:15  
I just tell my parts guy to give me a normally open oil pressure switch. He know what Im talking about. Most of what I do is on Ms and Hs, I put a tee at the gauge, put the switch in the 3rd hole, and wire it up.



[Log in to Reply]  [No Email]
John T

12-08-2010 12:16:55
66.244.97.31



Report to Moderator
 Re: Diode for alternator wiring - Which one is correct (p... in reply to AL Farmall Boy, 12-08-2010 09:55:08  
Jim has ya well covered and I (as usual) agree with his excellent advise, but FWIW I dont really recommend diodes anymore, I say use EITHER at least a 10 (or up to a 100 will work) ohm 5 watt resistor ORRRRRRRR an incandescent (NOT LED too much resistance) dash type small idiot/indicator light. The light or resistor affords some degree of current limiting protection better then a diode would and the light gives you a toofer as it excites the alternator PLUS provides a good visual indication of whats going on. Either still prevents backfeeding the ignition as the diode does.

Of course you dont need a 5 watt resistor, a smaller wattage rating would suffice, but they usually have bigger more robust easier to wire up leads

Some "dudes" even wire a resistor in paralell with the idiot light so if the lamp burns out the alternator still gets excitation wooooooo hoooooooo

Wonder if Jimbo concurs?????

Ol John T and all

[Log in to Reply]  [No Email]
Brownie 450

12-08-2010 12:08:44
66.43.241.198



Report to Moderator
 Re: Diode for alternator wiring - Which one is correct (p... in reply to AL Farmall Boy, 12-08-2010 09:55:08  
A 1N5408 is a 3 amp 1000 volt diode which is lots of over-kill. Price won't be much more than smaller units. A 1N4007 is a 1 amp unit with 1000 volts rating.



[Log in to Reply]  [No Email]
AL Farmall Boy

12-08-2010 10:59:42
74.248.177.194



Report to Moderator
 Re: Diode for alternator wiring - Which one is correct (p... in reply to MN Mike, 12-08-2010 09:55:08  
Thank you so much Jim. I am actually on my way to the electrical supply house, and will take them with me just to make sure of the rating of them. I am also going up there to purchase some new fuse holders (the original glass fuse style).

If you don't mind, please clarify these statements for me:

* The pilot light is used to excite the alternator and prevent current from "backfeeding".

* The diode is used to excite the alternator and prevent current from backfeeding.

* The 20 amp?? glass fuse holder (in the dash) is wired between the light switch and ammeter.

[Log in to Reply]  [No Email]
AL Farmall Boy

12-08-2010 10:35:18
74.248.177.194



Report to Moderator
 Re: Diode for alternator wiring - Which one is correct (p... in reply to CNKS, 12-08-2010 09:55:08  
Jim,
My question is: why is the diode with the higher rating ALOT smaller than the one from Radio Shack?? The smaller ones I got from the supply warehouse can be taken back. I bought 9 of them, so I would want to make sure I have the right/best one.



[Log in to Reply]  [No Email]
Janicholson

12-08-2010 10:42:03
199.17.6.126



Report to Moderator
 Re: Diode for alternator wiring - Which one is correct (p... in reply to AL Farmall Boy, 12-08-2010 10:35:18  
Neither is a 20 amp diode (just to be clear)
The rating may not reflect the size if the efficiency is better on one than the other (Full spec sheet needed) If the small one excites the alternator, give it a whirl. The filiment in a usable idiot light is way smaller then the leads on either diode. 150 ma is the filiment current in the bulb that will excite the alternator to charge. Jim



[Log in to Reply]  [No Email]
Janicholson

12-08-2010 10:31:06
199.17.6.126



Report to Moderator
 Re: Diode for alternator wiring - Which one is correct (p... in reply to AL Farmall Boy, 12-08-2010 09:55:08  
One milliamp is 1/1000 amp. The diode needs to handle about 150ma. I like a one amp diode just to be robust. Either of those should work they just might be closer to a spark or stray current breakdown. The PIV peak inverse voltage rating in more important to guard against the failure. 250 volts would be about right as it is connected in the ignition circuit (usually) and these are noisy. Jim

[Log in to Reply]  [No Email]
AL Farmall Boy

12-08-2010 09:57:03
74.248.177.194



Report to Moderator
 Re: Diode for alternator wiring - Which one is correct (pict in reply to Wardner, 12-08-2010 09:55:08  
Just for clarifacation, the one from Radio Shack is on the Left; and the one from the supply warehouse is on the Right. Thanks.



[Log in to Reply]  [No Email]
[Options]  [Printer Friendly]  [Posting Help]  [Return to Forum]   [Log in to Reply]

Hop to:

TRACTOR   PARTS TRACTOR   MANUALS
Same-Day Shipping! Most of our stocked parts ship the same day you order (M-F).  Expedited shipping available, just call!  Most prices for parts and manuals are below our competitors.  Compare our super low shipping rates!  We have the parts you need to repair your tractor.  We are a Company you can trust and have generous return policies!   Shop Online Today or call our friendly sales staff toll free (800) 853-2651. [ More Info ]

Home  |  Forums


Copyright © 1997-2014 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy

TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters