Current sense schematic question


Posted on Feb 6, 2014

Looking at different ways to do current sensing, using regular opamps, rather than dedicated chips like the MAX4073T/F/H, which work well, they are just rather expensive. So while poking around i found an article written by Bob Pease, , which talks about `error budgets` And the schematic fugure two, caught my eye As far i understood what Bob was talking about that curuit, should generate 2 volt on the output


Current sense schematic question
Click here to download the full size of the above Circuit.

if we have one amp through the shunt resistor, I decided to run the shcemati through an simulation tool or two to see whats up. In the one tool i tried where i had the PN4250 transistor, i consistently get around 6 volts on Vout, no matter what the current is. I tried in LTspcie, and that just gives me 11. 2 volts (see attached model, i dont know if the lm258 and the 3906 suitable for this) If you add a +14v (or more) supply just for the LM258 the circuit will operate correctly, otherwise you need an op-amp which functions with inputs close to its +ve supply which are not common. JensAndree, the hall sensor is 3$ in small quantiites, so its a bout twice the price of the max4073m but i guess that the hall sensor might be better over larger current ranges and with AC. looks very interesting, and i can see that you also found the mcp600x series opamp, i have found that that microchip has a lot of interesting analog parts. I am building a related system to yours, to power a server 24/7 using solar panel s and batteries, with a power brick as a backup. The current monitor pcb you saw in the post is 1oz copper and is easily handling +/- 15A. I would like to test the board at the maximum ATO fuse rating of 40A when I get the time. I think I will have to up the pcb copper to at least 2oz for that much current. Good luck with your project. I do all of the lighting in my house with LED lights I designed and all 24 lights are 100%...




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Voltage controlled amplifier
    Rejection filter
    10 To 15W Atv Linear Amplifier
    Arduino SFR Ranger Reader
    9V to 13.5kV Inverter Circuit Schematic Diagram
    magnetic switch circuit
    drm down converter for 455khz if
    garageshed alarm
    Delaying the release of DC relay circuit
    RC clock signal generating circuit



    Top