A Small 1980s Production Run
Frans van de Eng made Kallisto clocks in the second half of the 1980s. Roughly 50 were produced in three series, originally selling for 120 Dutch guilders.
Mechanical Appearance, Electric Timing
The wooden case, analog hands, flags, and top-mounted player buttons intentionally preserved the visual and operational language of the classic mechanical chess clock. Electric timing components replaced the spring-driven movements without turning the device into a digital clock.
Handmade Variation
Because production was handmade, small differences survive between examples. The maker described the case as exceptionally strong, even joking that it could support a person's weight.
Historical Significance
Kallisto belongs in the transitional space between mechanical and digital timing. It modernized the power source and internal operation while retaining the tactile and visual habits of analog tournament chess.