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Paralleling ACS750 sensors with opamp — Parallax Forums

Paralleling ACS750 sensors with opamp

JonathanJonathan Posts: 1,023
edited 2010-02-10 16:00 in Accessories
Hi All,

I am using some ACS750 hall effect curennt sensors, and want to read currents higher than their ratings. They are bidirectional, so with no current they put out 1/2 VDD, in this case 2.5 volts. I have rigged it up using 2 adc channels to read them, and it works fine. However, I want to use one adc channel instead of two.

The way I have them rigged in parallel, with current applied one will read more than 2.5V and the other less. I want to combine the outputs with an op amp to come up with a single signal to read with an ADC. I don't want any amplification, just to make it behave as if· it was one sensor. What type of op amp circuit do I need for this?

Thanks!

Jonathan

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www.madlabs.info - Home of the Hydrogen Fuel Cell Robot

Comments

  • Miner_with_a_PICMiner_with_a_PIC Posts: 123
    edited 2010-01-28 23:48
    Use a summing amplifier...this configuration will sum as many inputs as you would like to add and scale the result. It is recommended that you use a good quality instrument operational amplifier (I have OP177's laying around and these are super amps for this sort of thing), not the 741 unless you don't mind some error and drift issues.

    Try this link for more information on summing amplifiers..

    http://webpages.ursinus.edu/lriley/ref/circuits/node5.html#fig[noparse]:o[/noparse]psum
  • KatyBriKatyBri Posts: 171
    edited 2010-01-31 02:01
    Hi Jonathan,

    Iw ould like to try using the ACS750 hall effect curennt sensors, but have never used this type of device before. I looked at the datasheet. How to you connect them. Do they simply sit on the wire and "read" the current via induced current in the device, or do you cut the wire and attach each end to the lugs.

    For 220 vac sensing, would you just put one on the neutral(I think that is what it is called). I just want to sense when current is or is not flowing-I don't need to know how much.

    Thanks.
  • JonathanJonathan Posts: 1,023
    edited 2010-02-10 16:00
    Sorry it took me so long to reply, was away.

    Miner, I'll get a real instrument amp, all I hace ATM is regular op amps.

    Katy, you have to cut the wire. I soldered eyes on mine. Great sensors. I'd put it on the hot for AC.

    Jonathan

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    www.madlabs.info - Home of the Hydrogen Fuel Cell Robot
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