Synchronar watch history
How it came about
The Synchronar was one of the most unusual electronic watches of the 1970s, combining quartz timekeeping, red LED display and solar charging. Created by American inventor Roger W. Riehl, it evolved from the early Synchronar 2100 to the Mark IV in 1981. Its futuristic design, with solar cells on top and an edge-mounted LED display, made it unlike any conventional watch.
Roger Riehl and the Synchronar
Roger W. Riehl developed the Synchronar in the early 1970s. His goal was to create a practical solar-powered electronic wristwatch using quartz timekeeping, LED display technology and rechargeable batteries.
The name Synchronar came from Synchronous Chronometer Calendar. The watch was designed with a calendar extending to the year 2100.
The Revolutionary Design
The Synchronar was unlike a conventional watch. Large solar cells covered the top of the case, while the red LED display was placed on the side so it could be read by turning the wrist.
Magnetic controls allowed the watch to be operated without conventional openings in the waterproof case.
Mark I — 1972–1974
The first Synchronar, the Mark I, appeared in the early 1970s. It combined quartz electronics, red LED display, solar charging, rechargeable batteries and a long-range calendar.
The Mark I established the basic design that would remain recognizable throughout the later generations.
Ragen Semiconductor
Ragen Semiconductor became involved in production, and commercial Synchronars were produced from around 1974.
The electronics were extremely advanced for their time, using low-power CMOS circuitry to make solar-powered LED operation possible.
Mark II — 1975
The Mark II followed in 1975 with updated electronics while retaining the basic Synchronar design.
Mark III / Sunwatch — 1977
The Mark III appeared around 1977 and became associated with the Sunwatch name and Riehl Time Corporation.
The watch gained additional electronic functions while keeping the solar-powered LED concept.
Mark IV — 1981
The Mark IV, introduced around 1981, was the most advanced production generation.
It included functions such as:
-
time and seconds
-
date and calendar
-
two time zones
-
12/24-hour mode
-
alarm
-
chronograph
-
daylight-saving-time functions
-
accuracy adjustment
-
The End of Production
By the late 1970s and early 1980s, inexpensive LCD watches had replaced most LED watches. LCDs consumed far less power and were much cheaper to manufacture.
Riehl continued limited production, but the Synchronar never became a mass-market watch. Riehl Time Corporation eventually ceased operations in the 1980s.
The Synchronar Today
Today, original Synchronars are highly unusual collector watches. Many surviving examples still have their original cases and LED displays, but the batteries and electronics often require restoration.
Modern replacement electronics can keep the original LED display and case while replacing obsolete circuitry.
Modern Synchronar Development
Modern projects such as Seven-Segments continue the original idea by combining modern low-power electronics with original 1970s LED displays and cases.
The principle remains essentially the same as Riehl's original concept:
light → solar cell → rechargeable battery → electronic timekeeping → LED display
The Synchronar remains one of the earliest and most distinctive solar-powered LED watches ever made.