Amtex, a little known maker who employed the Hamilton-owned Standard Time Corp. 130E movement; the same as Andre Bouchard, Stratford and Vantage.
However, this watch is unusual in having a display back. The 130E is very similar to the Hamilton Cal. 505 and shares many of the same parts but Hamilton’s only electric watch with a display back was the rare Clearview. The movement can be seen running in my following YouTube video clip: