ˈʌðɚz jˈuːs ɐn ɛkstˈɜːnəl pˈaʊɚ səplˈaɪ kəmpɹˈaɪzɪŋ ˈiːðɚɹ ɐ tɹænsfˈoːɹmɚ ænd ɹˈɛktɪfˌaɪɚ, ɔːɹ ᵻlɛktɹˈɑːnɪk sˈɜːkɪtɹi.
Others use an external power supply comprising either a transformer and rectifier, or electronic circuitry.