I have a transformer without specifications. I only know the primary voltage and the secondary voltage. How to know what is the maximum current that a transformer secondary can supply?
An approximate simple method of determining the secondary current of a transformer is to measure the winding resistance. Then simply divide the voltage by the measured resistance to obtain the maximum current supplied by the transformer. For example, if we measure 12 ohms on a 6 V transformer, the maximum current of this transformer would be I = V / R = 6/12 = 0.5 A or 500 mA.
