http://i.imgur.com/TbYIHnb.png?1 So, if I have a pull up and apply a current source. How would I need to read/calculate resistance? V=IR I = 5V/8k = .0006A would result in a voltage drop of close to 5V Using a current source/Voltage reader I supply .0006A which should equate to ~5V drop But when I read my voltage reader I get 9.83V. Is this correct? Then my resistance would be 9.83/.0006 ~ 16.4k ? These calculations do not seem correct.