RV-500 requires the BOSS PSA Series AC adaptor (sold separately).
Note: The RV-500 draws 225 mA, so it must be used with the PSA-S or PSA-S2 adaptor (output 500mA). The PSA series has variations in the plug shape depending on the voltage of the sales region. Use the model suitable for your region. To learn more about the PSA series, see also this article: BOSS PSA adaptor: Specification Differences by Model
Caution: Use only the specified PSA Series adaptor. Use of any other adaptor may cause malfunction or damage to the unit.