Amateur Model (E.F. Johnson #114-515) Made by Logan and later, by Johnson.
Vibroplex Original style frame. 3" X 6 1/4" base. Black. Two paddles, no
circuit closer. Dot spring & stop are on separate screws, Vibroplex-style.
(Both functions are on one screw with most Speed-Xs). Wheel and post
Electro-Bug style damper. Model number may be on bottom.
Speed-X Model 520 (E.F. Johnson # 114-520) 1954, made by Johnson. Like
model 515 with circuit closer added and new E.F. Johnson nameplate.