Can the resistance ratio of a transformer be used to calculate the turns ratio?

Discussion in 'General Electronics Chat' started by Pleasedonthitme, Feb 11, 2016.

  1. Pleasedonthitme

    Thread Starter New Member

    Aug 29, 2013
    I have several transformers I don't know the values of.
    Could I compare the ratios of the resistance of each coil and use this to calculate the turns ratio (if the wires are different gauges, does this make a difference)?
  2. Brownout

    Well-Known Member

    Jan 10, 2012
    No, because the guage of wire is typically different for the primary and secondary. You can use the ratio of inductance.
  3. Papabravo


    Feb 24, 2006
    You can also apply an AC source to the primary and measure the secondary voltage. The safest way to do this would be starting with a known transformer to isolate the experimental unit from the mains.
    atferrari likes this.
  4. alfacliff

    Well-Known Member

    Dec 13, 2013
    use a low voltage ac for one winding, and measure the other, the voltage ratio will give you the turns ratio. if you use a higher voltage supply, the other winding, if a step up ratio might make a hazardous voltage.
    RichardO likes this.