hardtimes Posted March 16, 2012 Report Share Posted March 16, 2012 I've been studying circuits for all of about 24 hours, so i'm sure this question sounds a bit silly. Why are the two resistors on either side of the first transistor dumping to ground? http://www.electronics-lab.com/projects/sensors/002/index.htmlIf i understand resistors right, in that situation there wouldn't be any pull through them since they are jumping out of the circuit prematurely. with no pull, they aren't providing any function. Obviously i'm wrong. Someone school me :) Quote Link to comment Share on other sites More sharing options...
Hero999 Posted March 16, 2012 Report Share Posted March 16, 2012 Are you talking about R2 and R3?They pull the bases of the transistors down to 0V when there's no signal. Without R3 and R2, it's possible some noise could turn on Q1 or the leakage through Q1 could turn on Q2 and generate a false alarm.This isn't the best way to do it. Because DC is passed through the water, the probes will corrode over time due to electrolysis. This can be solved by using AC which doesn't cause electrolysis or corrosion. Quote Link to comment Share on other sites More sharing options...
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