Master clock

As a master clock or master clock that clock is called in a clock system that controls any number of slave clocks or watches daughter and therefore guarantees an exact synchronous transitional period, all connected clocks. This is important for a consistent timing within companies, government agencies, schools and other public buildings.

A second meaning of master clock says an evacuated precision clock that contains no moving parts except a temperature compensated seconds pendulum. These are outsourced to avoid mechanical disturbances in a synchronized with the master clock secondary clock (see Riefler and Shortt clocks ). This could be reached per day for time services long before quartz watches transition accuracies of less than 0.01 seconds.

Design and function

The master clock is the most important part of a clock system; their task is the control of slave clocks and additional signaling devices. It is usually not installed in a location where the display, and the dial is clearly visible, but in a control room, along with Other communication technology or electrical installation.

Master clocks have a very precise rate under the relevant technology. The master clock is made of the movement and the drivers for the clock lines. At regular intervals, usually every few minutes, a short control signal to the subordinate slave clocks is emitted. Characterized in that the position indicator is driven by a stepper motor. To reduce the effects of interference on the line, which could affect the synchronization of the clocks, sequential control signals are emitted with opposite polarity. If your watch has an older design, the polarity of the control signal is reversed by a Polwenderelais.

Multiple clock lines are, in practice, particularly with extensive facilities, furnished, to each of which a certain number of slave clocks can be connected. Each line can be individually adjusted, and where appropriate to disturbances such as short circuit, short to ground or an open.

Until the advent of quartz-controlled watches was the movement of the master clock from precision molded precision engineering. The transition was regulated by a precisely adjustable pendulum and are stabilized by evacuated enclosure. In order to prevent change in length of the pendulum during temperature fluctuations, thus reducing gear inaccuracies, it is often made of invar steel.

Main mechanical watches are distributed as ¾ -second pendulum design and as a 1-second pendulum design. ¾ -second clocks form the predominant component. 1-second clocks are used particularly in clock systems of stations and were until about 1960, the basis of astronomical time services.

Modern home watches cheap in Germany from the time signal of the long-wave transmitter DCF77 in Mainflingen near Frankfurt am Main, to synchronize with the official time. In other countries, are, respectively, there were comparable time services, such as the BEV in Vienna, the former HBG transmitter Prangins or OMA in Prague.

Most special master clocks are used with additional switching outputs and DCF77 time receiver for churches. These control the clock tower (usually 230 V ), possibly secondary clocks (12 V or 24 V pole-changing ) as well as outputs for Läuteglocken and impact bells ( pulse output for the percussion).

Some special features for church master clocks:

• When melodic ringing several Läuteglocken be offset in time ( according to size ) on and off.
• When Uhrschlag can be issued every quarter hour melody (eg Westminster) and then the hour strikes.
• The percussion lock prevents possibly with Nachverriegelung, a beating if the bell is ringing, or is not yet settled.