Reduce Power Source Sensitivity

  1. I am currently designing an electronic circuit to detect fluctuations of the geomagnetic field in response to solar activity.

    One problem I am anticipating however is an over sensitive power source which will respond to thermal fluctuations in the holding room (can’t control room temperature) etc.

    A method I have considered to correct this is to use a bridge circuit and by controlling the resistor component ratios simply, consequently maintain a consistent power input.

    Any opinion on this potential method or a more effective one would be greatly appreciated.
     
  2. jcsd
  3. berkeman

    Staff: Mentor

    Welcome to the PF.

    Can you say more about your power source? What are the input and output voltages, and what is the range of the output current? What is the variation in the output current versus frequency? Is it a very steady output current?

    To get an ultra-stable output voltage, you would typically use a linear voltage regulator with good output bypass capacitors. If needed, you could put the regulator in a temperature-controlled enclosure as well.
     
  4. uart

    uart 2,776
    Science Advisor

    Hi Calum. In situations like this you generally have two options. One is to try to improve the power supply stability, the other is to try to make your design more resistant to power supply variations.

    We need to know a little bit more about your detector and associated instrumentation amplifiers before we can assess what options you have for increasing the PSRR (power supply rejection ratio) if this turns out to be a problem.
     
  5. [ Circuit Setup.jpg

    Hello, thank you for your valued feedback. Unfortunately I don't have much information noted down concerning the power supply but I do believe the power input ranges from -12V to 12V if memory serves correct.

    I have attached a shematic description of the current circuit plan (excuse the messiness) if that is of any help. My apologies I won't be back in the lab till next Tuesday when I will hopefully be able to update both of you with more details of the power supply.
     
  6. berkeman

    Staff: Mentor

    Why is the input opto-isolated? (Even though the input light source shares the same ground as the measuring circuit...)
     
  7. uart

    uart 2,776
    Science Advisor

    Don't worry too much about the power supply a this stage. What we want to see is how well your design rejects power supply variations. Unfortunately I can't discern which is the transducer and first amplification stage (of transducer output) from the circuit diagram shown.

    Can you please explain exactly what transducers you are using and what first stage the transducer signals are feeding in to.
     
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