Mark Rages wrote: > On Wed, Mar 31, 2010 at 3:19 PM, ivp wrote: > >>> You are exceeding the common-mode range of the opamp by having >>> 10v/2 going into each input. >>> >> Bob, do I have an issue with this circuit, bearing in mind that the meter >> now zeroes and the output (from subsequent stages) is a linear 4V / 1000rpm, >> with no baseline offset ? >> > > No, you are still exceeding the common-mode voltage range of the > TLC271. At 10V supply, the common-mode range is 0.2 to 9V minimum. > This is measured from the negative supply, so max CM voltage in > circuit is -5+9, or 4 V. > > Regards, > Mark > markrages@gmail > > -- > Midwest Telecine LLC > markrages@midwesttelecine.com > ditch the LM385 and put a pair of potential dividers to reduce the voltage and increase the opamp gain to compensate. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist