Rate Finder

MicroSet can be ordered with an optional Rate Finder Mode. The purpose of the Rate Finder is to calculate the correct rate for any running pendulum clock. How is this possible? By literally counting the Beats Per Hour of the clock. The Beats Per Hour of a clock are the number of beats it takes to drive the minute hand around once. It doesn’t matter if the clock is running fast or slow, it still takes the same number of beats to move the minute hand around once. If we can count the number of beats in one rotation of the minute hand, we know the correct BPH of that movement. Then we can adjust the current rate to be correct.

The Rate Finder includes a new sensor jack for MicroSet and a special magnetic sensor to count rotations of the minute hand. This jack is located above the standard sensor jack. The standard optical sensor is used to count swings of the pendulum. Every time the minute hand goes around, MicroSet divides the total number of pendulum swings by the number of minute hand rotations and derives the average Beats Per Hour to two decimal places for that movement. The Rate Finder will run for as long as you want it to. Each hour the result gets more accurate. You can judge for yourself when the readings no longer change and are correct.

As an example, the Rate Finder was being tested on a Hermle model 771 with an 18 cm pendulum. The Hermle literature states that the correct rate for this movement is 9722 BPH. The Rate Finder reported the following readings for the movement:


We were puzzled by the discrepancy between our measured results and the correct rate. We looked at the back of the clock, and it was stamped “162.00” Beats Per Minute. This is equal to 9720.00 Beats Per Hour. The Rate Finder was correct and the Hermle literature was wrong.

The graphs below show measurements taken on an inferior time only movement made in India. This movement represents pretty much a worst case for the Rate Finder. There is a lot of slop in the pivots and also in the minute hand. The first graph shows the raw beat count of each rotation of the minute hand. The individual counts vary by as many as 50 beats per hour!

Raw graph

The next graph shows the running average of beat counts that the Rate Finder displays. The scale of this graph is ten times finer than the previous graph. Each grid line represents a change of only one Beat Per Hour. The Rate Finder revealed the correct rate for this sloppy movement within five rotations of the minute hand.

Also note that the 85 counts shown in the graph were collected in just 20.4 hours. This is accomplished by replacing the normal pendulum with a lightweight short one that runs much faster, which caused the minute hand to make a complete rotation in just 14 minutes. The correct rate was determined in a little more than one hour.

The Rate Finder requires the addition of a new jack to the timer and a new magnetic sensor for the minute hand. All “modern” MicroSets can be upgraded to contain the Rate Finder. If your timer says
-= MicroSet 2 =-
-= MicroSet 3 =-“
when you turn it on, you will be able to add the Rate Finder. If your timer says only
-= MicroSet =-
it is too old to be upgraded.