Abstract: A method and system for testing the accuracy of the oscillators of electronic clocks includes transforming a frequency signal corresponding to the output of a clock oscillator into a non-sinusoidal signal having the same frequency as the frequency signal and filtering the non-sinusoidal signal to pass a component of the non-sinusoidal signal having a frequency associated with a reference frequency to be compared with the signal passed by the filter such that clock oscillators operating at various frequencies of which the reference frequency is an integral multiple can be tested since the non-sinusoidal signal, which is preferably a sawtooth signal, contains harmonic components corresponding to the reference frequency.

Abstract: A circuit arrangement for the control of a forward-rearward-counter with at least one manually actuatable switch over which the reversing input of the counter can be triggered with different potential and the count input with count pulses. A first anticoincidence member has two inputs connected with one another over a resistor, one input being triggered via the switch. A second anticoincidence member has two inputs, one of which is in connection with the count input of the counter and with the output of the first anticoincidence member. The output of the second anticoincidence member is connected to the reversing input of the counter. Both anticoincidence members are applied with count pulses at their free inputs.

Abstract: The invention relates to a wind direction indicator for sailboats wherein a rotatably mounted permanent magnet connected to the shaft of a weather vane is employed as a pick-up. By means of its magnetic field, it controls, in dependency upon the wind direction with great respect to the midship line two magnetically controllable semiconductors mutually displaced by an angle of 90.degree.. This is an improvement over U.S. Pat. No. 3,791,211.

Abstract: An electronic clock, such as a quartz-crystal clock, is tested and may be adjusted by measuring the oscillation frequency of the clock with an active antenna. The oscillation frequency is electrically compared with a reference frequency to determine deviation and provide an output indication. Internal calibration is carried out when the system is not being used for testing.