Accurate

For the time that I have been interested in and working on Synchronous Electric Clocks I've become more impressed with them.

Some come in great Art Deco style cases, some in very simple but appealing wall clock styles. Many people remember the shape and style from school days or factory days where these clocks were used.

Many early clocks in the 30s were in Bakelite cases, making them doubly collectable.

There are also some great Amercan synchronous clocks especially the advertising ones.

This really is a great collectors area as prices are relatively low for a clock type that generally has a very robust and repairable movement.

These clocks use the frequency of the mains to keep their accuracy. The mains has to be kept in sync otherwise you would end up with 0 volts at your sockets!

The mains, certainly in the UK, is not going to be switched off or changed to 25vDC ( they tried that in 1910)

Have a look at the real time mains data.

My recent test to the left proves the point

June
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30

July
1
2
3
4
5

Sun

8
15
22
29

Aug
5
12
19
25

Sep
2
16
23
30

Oct
27

6pm
set exactly
+11
+1
-2
-8
-12
-8
+11
+11
-1
+6
+7
+21
-4
-1
-35
-24
* 0 *
+11
+11
+9
-5
-13
+9
-13


-10
-25
-1
+7
* 0 *

8am
-------
+18
+5
+7
-16
-6
-10
* 0 *
+4
-10
-9
* 0 *
+20
+22
-3
-24
-37
-3
+7
+10
+15
-2
* 0 *
+8
-10


-29
-30
-7
+4
+3

measured

I measured the time of my Ferranti synchronous electric mantel clock against my radio quartz clock.

The figures are seconds infront (+) or seconds behind (-) the time shown by the radio clock at 8am and 6pm each day

Maximum deviation 37seconds

Absolutely accurate 5 times

At the end of the month test - absolutely accurate (pure luck)

I can pretty much guarantee that at the end of 6 months the clock will be no more than 37 seconds out.

I'm going to measure it weekly and lets see !

None of my antique mechanical clocks will be that accurate. I should test a regular quartz clock !

OK

So, after 5 months of running my trusty Ferranti Synchronous motor clock, it is 20 seconds slow.

During this period....

I had no mains power cut

The clock didn't stop

The mains frequency wasn't changed here or any other country

It didn't blow up, catch fire or electrocute anybody !!

It draws a tiny 1.7Watts to run

It may be just a slave to the mains frequency but what a great clock

June and July 2012

on each Sun

+1
+7
+2
+11

-24
-4
+11
+2
 

-4
+12
-5
+34

-20