@winoguy17 Just to be clear, you need to select a step down transformer (SDT) that best matches your wall AC mains voltage. Again you need to check your AC mains voltage at the wall outlet.
If your mains voltage average is 120Vac or less then a 115-120Vac to 100V SDT would average an output closest to 100Vac.
Example
https://www.bhphotovideo.com/c/product/964851-REG/acupwr_ajd_300_ctoc_japan_to.html.
If the wall outlet mains voltage is higher than 120V, say 122V, then a 115-120Vac to 100Vac SDT would not be a good choice, imo. The output voltage of the SDT would be higher than 100Vac.
If the mains voltage averages higher than 120V, say 122V, maybe 123V, then the 125Vac to 100Vac SDT would be a better choice. The average output voltage of the SDT would be closer to 100Vac.
Example
https://acupwr.com/collections/japan-to-usa-transformer-converter-use-100-volt-appliances-in-110-vol...
If you can find a SDT that is rated at *120Vac* to 100Vac that would be fine for a mains voltage that ranges from 118Vac - 122Vac.
If the mains voltage is below 120Vac then the SDT would output slightly below 100Vac. With a mains voltage above 120V the SDT output voltage would be slightly above 100Vac.
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