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OPA541: Howland Current Pump for Helmholtz coil

Part Number: OPA541
Other Parts Discussed in Thread: OPA549


I'm trying to build a current drive for Helmholtz coil following the designs in

To obtain higher current, I plan to use OPA541 in place of LM657. Are there any potential issues for using OPA541 in this circuit? Is there a better op amp to use here to achieve high voltage (30V) and current (>5A)? Thanks!

  • OPA541 is a good choice to meet your high +/-30V voltage supplies and output current (>5A) needs.  The only other part that I am aware to be able to meet these requirements is OPA549.

  • Hi Marek, I built the circuit but found the output to be independent of the input voltage Vi.

    Here are some measured voltages:

    V- = 1.3  V

    V+ = 1.1 V 

    Vo = 14 V

    Io = 2A

    Would the above indicate that the op-amp is damaged? Thanks!



  • What are V- and V+?  I hope these are NOT supply voltages since the minimum supply for OPA541 is 20V (or +/-10V) and the minimum supply voltage for OPA549 is 8V (or +/-4V). If you need further assistance, a picture is worth thousand word - please attached circuit simulation schematic by clicking on INSERT button below the active window.

  • I'll close this thread for now.  If you need further assistance, please reply or start a new E2E inquiry.