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I have connected circles, but I dont know what is this exactly and do I need them on a PCB?

enter image description here

full scheme

thanks for feedback.

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  • \$\begingroup\$ Have you read what the accompanying text says? \$\endgroup\$ – Ignacio Vazquez-Abrams Dec 18 '16 at 9:01
  • \$\begingroup\$ I dont have any accompanying text, I have only scheme and need to create pcb for it. \$\endgroup\$ – LyndaOlexandr Dec 18 '16 at 9:06
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    \$\begingroup\$ Where do the circuit nodes connect to? (That are cut off at the bottom of your fragment of the schematic diagram? Perhaps it is a current shunt to measure the battery consumption. Impossible to answer you question without better context. At least seeing the ENTIRE circuit including the OTHER ends of the "A" and "B" connections. \$\endgroup\$ – Richard Crowley Dec 18 '16 at 9:07
  • \$\begingroup\$ I will add full scheme to description. \$\endgroup\$ – LyndaOlexandr Dec 18 '16 at 9:13
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    \$\begingroup\$ I think you will find they are two taps on a piece of wire, which acts as a current measuring shunt. The resulting voltage is filtered by R2,C1 and amplified in DA1-1 to provide a measurement of the current drawn from the battery. There is no information about the dimensions fo the shunt, or its resistance, so you will either have to find the relevant documentation or reverse engineer from an actual unit, or guess what you think the resistance (and therefore current measurement gain) should be. The circles may indicate a sliding tap, i.e. adjust on test. \$\endgroup\$ – Brian Drummond Dec 18 '16 at 10:13
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The connection between (A) and (B) is a current shunt. The amplifier DA1 senses the voltage difference between (A) and (B) to measure how much current is coming out (or going in) to the battery GB1. That shunt could be a special trace on the circuit board. Or it could be a piece of wire as @Brian Drummond suggests.

You cannot successfully copy this circuit without some knowledge of the resistance value of that shunt. That information is not shown in this schematic diagram.

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