New in this version: switching off the tubes by push button - bugfix in 7971 mode
Switching off the tubes by the DIMM button While in normal mode, press the UP/DIM button repeatedly to rotate through the 4 brightness levels. The OFF_Level switches the tubes off but the clock still works. Maximum brightness is the default level at power-up. Note that the eye-catching fade effect during digit transitions is only on the highest brightness level. In the 3 lower brightness levels, the digits change instantly. Remember that manual brightness setting is deactivated if the LDR feature has been installed.
