Connectors on a breadboard have some resistance, when prototyping a current sense circuit with a 0.01 ohm resistor can the connectors resistance affect the circuit? and if yes how can we prototype sensitive circuit like this?
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asked Oct 5, 2019 at 6:56
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1\$\begingroup\$ How much current? \$\endgroup\$– Leon HellerCommented Oct 5, 2019 at 7:01
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\$\begingroup\$ @LeonHeller max 5A but not on a breadboard, for testing on a breadboard up to 1A... \$\endgroup\$– ElectronSurfCommented Oct 5, 2019 at 7:02
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1 Answer
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Breadboard prototypes are meant to verify the basic operation conditions of a circuit. They are not meant as a replacement of the "real thing".
Also breadboards are only suited for prototyping simple circuits. Nobody would prototype e.g. a 3GHz circuit on them. Use your breadboard to check if the results are nominally correct, then go to the real thing.
In this case you make a reasonable 'current' sense circuit by keeping the sense resistor with the main current connectors outside the breadboard. (You can make them as big as you want). Then only connect the voltage sensing lines.
Had troubles to remember the name ( I am getting old): Kelvin Circuit!
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\$\begingroup\$ Thanks, Side question; if we pick the resistor even smaller like 0.001 ohm how can we avoid copper connections resistance on the board to affect the circuit? is putting the sense resistor and op-amp right next to each other enough? \$\endgroup\$ Commented Oct 5, 2019 at 7:19
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2\$\begingroup\$ If you really want accuracy get yourself a special current sense resistor. They have the standard four leads: two for current, two for voltage. Try googling "current sense resistor" \$\endgroup\$– OldfartCommented Oct 5, 2019 at 7:25
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\$\begingroup\$ For anyone interested in this topic: google "4 terminal current sense resistor" and also This. \$\endgroup\$ Commented Oct 5, 2019 at 7:53