|
Farmall & IHC Tractors Discussion Board |
Re: Odd Resistor Electrical behaviour
[ Expand ] [ View Follow Ups ] [ Post Followup ] [ Return to Forum ]
Posted by JB on January 19, 2004 at 19:48:05 from (24.157.143.220):
In Reply to: Odd Resistor Electrical behaviour posted by Dave Craft on January 19, 2004 at 19:11:26:
Hi, the resistor probably requires a load to cause it to fail. Connect a 12V light bulb from resistor to ground and see if it glows dimmly or not. Problem reading the load end of the resistor with a volt meter is that the volt meter draws so little current that the voltage drop across the resistor is almost 0 and hence you read 12V. This is especialy true for digital volt meters as they require only micro amps of curent to read voltage. In math terms Voltage across Resistor = Current x Resistance. If current require for digital meter is 10 micro amps (10 x 10-6) and resistor is 5 ohms then voltage drop across resitor would be (10 x 10-6) x 5 = 50 x 10-6 or 50 micro volts.
So if you had a 12V battery connected to the resistor and a digital volt meter on the load side of the resistor the volt meter would read 12V because the -50 micro volts is to small to read.
This is the reason to connect a 12V light bulb on the load side of the resistor and it should draw 1 or 2 amps and the voltage drop across the resistor should be from 5 to 10 Volts. Sorry for the ramble but was an electronics troubleshooter for many years. JB
Follow Ups:
Home
| Forums
Today's Featured Article -
An Old-Time Tractor Demonstration - by Kim Pratt. Sam was born in rural Kansas in 1926. His dad was a hard-working farmer and the children worked hard everyday to help ends meet. In the rural area he grew up in, the highlight of the week was Saturday when many people took a break from their work to go to town. It was on one such Saturday in the early 1940's when Sam was 16 years old that he ended up in Dennison, Kansas to watch a demonstration of a new tractor being put on by a local dealer. It was an Allis-Chalmers tractor dealership,
... [Read Article]
Latest Ad:
Variable pulley for case 1530 skid loader
[More Ads]
Copyright © 1997-2024 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 HeadquartersWebsite Accessibility Policy |
|
