For your information, clock 707 would date to about 1919 and would (probably) have originally been in a 'false pediment’ type case, found (mainly) between the approximate serial number range of 680 (a

Howard, your clock would date to circa 1935 - but you probably kew that anyway! John

I can’t comment on power consumption as I run several clocks from a float charged battery (multiple C sized NiMH cells - now about 15 years old) - but 280 mA is on the low side for a Synchronome. 300

Interesting. The Silent Electric (closely related to early GPO clocks) uses make before break and resistors (unknown, but very probably just like the GPO ones). The were designed to work with Silent E

If this is done in the musical world - then I think the assumption that any effect on the timing (i.e. lengthening of coil current duration) is insignificant. In a clock circuit, if you do get the pol

I do just as you suggest on all my dials and masters. 1N400X series diodes. The maintaining of current is minimal (looked some years ago with an oscilloscope and it was insignificant). There is typica

Can anyone explain why we stick with the Synchronome resistor? I can make a few guesses; In a Synchronome, the ‘ON period’ is very short - a few hundred milliseconds per minute, so the losses in a res

There were a couple of Synchronome ones listed on eBay a year or two back, if I remember rightly, one in a large metal case, the other in a wooden case.

A bit ‘off topic’, but there are three very good books on ‘Country House Technology’ and lighting; Technology in the Country House by Marylin Palmer & Ian West Country House Technology by P.S. Barnwel

There were a number of optional ‘quiet’ designs for 30 second single polarity systems by both Synchronome and Gents - as well as the Silent Electric slaves. Some earlier G&J versions were also rather

It looks a very nice original clock.

The small ‘coil’ behind the plate is a wire wound resistor in parallel with the coil - just as you say, for spark suppression. Resistance is roughly 10 x the coil value. Similar resistors are used on

Slightly off topic, but this sort of thing has come about (at least in part) due to the current plague of TV programmes on ‘restoration’ and ‘re-purposing’. I’m not talking about the Repair Workshop,

The ’top chop’ is usually brass on earlier clocks. I don’t recall seeing one in anything other than brass. My most recent clock is early 1960s and is brass. See photo (which is an early clock). There

I can’t explain why your clock appears to be different, but all clocks I have come across use the chassis - and in fact, the armature contact isn’t provided with any way of insulating it from the chas

To clarify, the top terminal connects to the gravity arm side of the switch. Usually the connection is a loop of wire. The armature side of the switch connects to the chassis (some clocks have a small

The coils are indeed connected in series - and the (one) resistor is in parallel with the two series coils. Its value is roughly 10x that of the coils. The coils are connected to the chassis at one en

The “Rule of Thumb” was mainly to select the battery size ( as you note, fixed Voltage), then as I mentioned "a series resistor to limit the current (it won’t need much) to approx 300-350 mA”. By the

As a ‘rule of thumb’ allow 3 Volts for the master movement and 1.5 Volts for each slave movement ………. then use a series resistor to limit the current (it won’t need much) to approx 300-350 mA. 330 mA

Some notes I have compiled follow. I am very happy to take corrections/amendments. These notes are based on both my own ‘trials and errors’, and the material in Chapter 13 of “Synchronome : Masters of