Hi,
I am trying to build a little circuit that will detect a voltage difference that is greater than 100mV
between any two batteries. I though it would be easy but it turns out to be more complicated
than the project it will be used in...
I am using an opamp (lm358n) in its differential amplification setup in order to find the difference
of the voltages applied on its inverting and non inverting inputs. I have built a little split supply
circuit which powers the opamp with Vcc+ and Vcc-
I am also using a custom voltage reference of 100mV with a 3.0V reference transistor and a
adjustable voltage divider.
I will be comparing the 100mV reference with the output of the differential opamp.
So far so good. Everything works fine, but,
The problem is that the difference of the two sources could be either positive or negative,
depending on which opamp terminal you have connected the higher voltage source.
(I discovered that afterwards... that's why I've also built a split supply circuit.)
So my question is:
Is there an electronics configuration equivalent to the mathematics ABS(x) function?.
Or even better is there a way to do the same thing by powering the opamp with a single supply?
I have found the following solution but it uses two more op-amps (!) and a diode.
http://www.ti.com/lit/an/sboa068/sboa068.pdfOne of the authors is David Jones... Synonymy?
Thanks.