# Current trough sheet resistance

Hi everyone,

i have a very silly question but i prefer to ask befor doing sth wrong.

How much current (A) can resist a normal sheet resistance??

I am trying to build a currentsensor with arduino for my RC -car with an ACS770. I measured that the motor of my RC-Car gets max. 170 A.

Now im trying to build a circuit to get at least 50-100A to test my built, but i dont have any current generator.

Ive thougt if a get 5v of Arduino or 9v of a baterry and I use a 10 1 Ohm resistance parallel I will get 50 or 90 A....

How can i do that, I dont think the thin cables of a sheet resistor can handle so much current?? Arduino can handle only 500mA and a normal 9v battery also cant handle 90A.....

What did you use to measure that 170 A ? A multimeter?

First of all, I kind of doubt the 170A measurement for an R/C Car. Peak currents in motors are very difficult to measure accurately. I would assume that the max current could top 80A however. What I would suggest is to look at some application notes on TI.COM's website (Texas instruments). You will also need to read up on high current measurement as well since the resistance you will need will be very small since a motor load of 5V @80A is only 0.0625 ohms! The other approach is doing it magnetically with a hall type sensor which is easier, but not as accurate.

Big currents like that can be measured by using the motor wires as a current sense resistor. Clip one lead of your DMM to one end of the wire, and the other lead to the other end of the wire. Set your DMM to e.g. 200mV. Leo..

Those components are not "sheet resistance " they are film resistors. They will take a current that is limited to the power dissipation of the component.

Sheet resistance is the bulk surface resistance of a material and is measured in ohms per square. Note there are no units on the square as the units do not matter only the shape.

Conrad website, so maybe translated from German (kohleschicht), which means carbon film. Leo..

Hi,

I measured that the motor of my RC-Car gets max. 170 A.

What did you measure it with?

Now im trying to build a circuit to get at least 50-100A to test my built, but i dont have any current generator.

Yes you do, the RC car motor and what ever you measured the 170A with.

Tom..... :)

If you really want this kind of peak current, find a low ESR, high value cap. Charge it up and throw the switch.

You will probably need to replace the switch after every cycle. 8^)

I have heard stories of folks welding wrenches to a large electrolytic.