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[on:]

Is there a commonly used sensor for measuring current that can be placed on a breadboard?  I'm a little curious how much current my project is using at any given time (max of 2.5A).  I'd prefer the chip to have an analog voltage output.  I did come across the ZMC10D-ND chip, but I was wondering if that chip is the one that's typically used or this purpose

[Reply #1 on:]

Is there a commonly used sensor for measuring current that can be placed on a breadboard?  I'm a little curious how much current my project is using at any given time (max of 2.5A).  I'd prefer the chip to have an analog voltage output.  I did come across the ZMC10D-ND chip, but I was wondering if that chip is the one that's typically used or this purpose

Well if your just curious or need to characterize a circuit for sizing of a permanent power supply, you are better off just wiring in your DVM meter in it's current measurement mode and monitor. However if you have a application that requires controlling something based on current flow then there are two common methods, using a low ohm shunt resistor and measure the voltage drop across it via a analog input pin, or use a hall effect sensor that has the proper scaling for measurement of the current range you are wishing to measure. Here is one useful example, not cheap, but useful:

http://www.sparkfun.com/products/8883

Lefty

[Reply #2 on:]

The ACS712 is a common choice. SOIC-8 package but you could solder some wires to the pins to use on a breadboard.

BTW that link to the ZMC10D-ND doesn't seem to work.
______
Rob

EDIT: Same chip retrolefty pointed to, I forgot about the SF breakout board.

[Reply #3 on:]

The below might be an option.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=ZXCT1009FCT-ND

[Reply #4 on:]

you are better off just wiring in your DVM meter in it's current measurement mode and monitor

Sorry if I was unclear, it's more of a weak desire rather than a curiosity.  I'm building a user interface on my computer that will be showing live stats from my robot.  Voltage, temperature, position, etc, I am interested in adding current measurement to that list.  I'm looking to send the data to a PC, so using a multimeter wouldn't be adequate since it only displays the info on the device rather than outputting it in any way I can use.

I'm looking through the docs on the ACS712 and Parallax's breakout board for it - at first glance this device seems to be limited to measuring current on 5V supplies.  I'm using a 12V battery and then using three 5V regulators to power different parts of my robot.  While it would be a bit costly, I could get three chips to measure the three regulators, but there are also a few components that feed directly off of the 12V, meaning I'd still be missing some of the current draw for the whole system.

BTW that link to the ZMC10D-ND doesn't seem to work.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=ZMC10D-ND

I'm rather hesitant to work shunt resistors and soldering wires to pins, partly because it involves multiple parts (I was hoping there would be a single component solution to this problem) and partly because I lack a soldering gun at present, but could acquire one if no other solution is viable

[Reply #5 on:]

I'm looking through the docs on the ACS712 and Parallax's breakout board for it - at first glance this device seems to be limited to measuring current on 5V supplies

 The 5v is the supply voltage to the sensor. You connect 5V, GND, and sensed output to  the Aurduino Then, you put IP+ and IP- in series with the 12V or 5V power supply circuit that feeds the robot. 


 12+______+IP__IP-_______+robot-____GND-

[Reply #6 on:]

The measured voltage on the ACS712 is isolated from the other half of the chip, so it doesn't matter what level it is as long as its < than the isolation rating.

______
Rob

[Reply #7 on:]

The isolation rating is 2100V!   However you need to pot the circuit board in silicone to get that in reality as the air will likely breakdown first.  Many of these devices are Hall sensors so there's no electrical connection between sensor and the current being measured, just a magnetic field.  There are others than measure/amplify the voltage across a low-value 4-terminal resistor - these do require the voltage to be low but have greater precision - its also a better technique for low currents where the magnetic effects are tiny.

[Reply #8 on:]

A cheaper alternative would be the ACS711, it has a lower operating voltage of less than 100v so it should work aok for your application. Make note tho that the stated sensitivity is for 3.3v supply, it would be different for 5v.