Electric Masters

PO36 Hipp Toggle

GPO Clock Nos.36, Hipp Toggle Master Clock

The Hipp Toggle type of electric impulse, one of the earliest electrical types of impulse for a clock, was invented by a Swiss watchmaker called Matthaeus Hipp in 1838. The whole principle of the Hipp Toggle is based on giving the pendulum a 'push', or more correctly an impulse, only when its swing, or amplitude, drops below a certain level. This is achieved by having a little vane or toggle, that is attached to some electrical contacts, interacting with a catch attached to the pendulum rod.

The majority of the time the toggle and the catch don't interact with one another. However when the amplitude falls and the catch operates, it closes some electrical contacts and energisies an electro magnet. This in turn attracts the pendulum, in much the same way as if you had given it a nudge with your finger to keep it going.
The catch actually consists of a small block made out of the mineral 'agate' This is chosen because it is hard wearing and non metallic. A 'V' shaped notch is cut across the top surface, and a vane, the toggle, is positioned in such that a manner that whether or not it catches depends on the pendulum's amplitude. The agate block from my clock is shown below, along with a link which shows in photo's what is almost impossible to explain. A picture is worth a thousand words.......

For a full illustrated explanation of Hipp Toggle operation see here.

This block is located on a bracket which is attached to the pendulum rod about half way down. If you look at the top picture of the clock above and follow the line of the central wooden glazing bar, until it meets the pendulum rod coming down, you will see this block sticking out to the left a short way up the rod.

For a full illustrated explanation of Hipp Toggle operation see here.

The name 'Hipp Toggle' therefore is a generic name for clocks that employ the Hipp principle, rather than the name of the manufacturer. The clock shown above was made by Magenta, and was  built in the 1950's for the General Post Office for use in one of their telephone exchanges. The GPO employed several manufacturers to make their clocks, but they were all built to the same GPO specifications.
And as a sixteen year old apprentice these were also the first examples of a master clock that I had seen, thereby kindling my interest in master clocks for years to come.

These can be very reliable clocks which will function for years with little or no attention.

A common mistake that collectors make with these clocks is to run the slave dial, or in some cases more than one slave, direct from the clock (I plead guilty your Honour). The 30 second contacts, and also the one and six second contact sets, are not capable of handling the 200+ m/a that a slave dial requires. The contacts were designed to drive a 5000 ohm 50 volt relay inside the 'Clock Unit GMT 34' relay set. The relay-set in turn fed the slave clocks and also a programmer (Clock 70A) with the necessary pulses. So for domestic use a small relay should be deployed.
Failure to do so will eventually mean that the contacts will become pitted and instead of one clean pulse to the slave, you either get multiple pulses, or none at all. So if your Hipp has started behaving erratically, then that may well be the reason.

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