Some years ago I made (and still use) some constant current units. The design is from the LM317 application notes. Details attached;

The master draws 300 - 350 mA …….. but the duty cycle is low; approximately 100 - 150 mS every 30 seconds, so the average is low. J

OK, what I actually do is quite different as I have a large system with a distribution board etc. If you have no risk/worry over power cuts, then a ‘wall wart’ type adaptor is fine. If you get power c

You will have to try it. It is entirely possible the bob is a replacement, but the weight is not ‘critical’. The rod itself is quite light, so the bob dominates the CoG. You might have to extend the t

I have just had an (approximate) as they are running measure. Clock No 1 - Lead bob about 16 lbs I believe - fitted with light early type weight tray. Approx 90 cm from top of lower brass suspension b

The ‘notch’ is really a little file cut - and I don’t think it was always used, but I have seen it on some of my clocks. It was not very accurate because things varied. A variety of bob shapes and var

Perspex works well and is easy to work. It also looks almost indistinguishable from glass. You can buy a rod of perspex very reasonably and make the rollers in a small lathe. Glass is more difficult,

Glass is correct. I have also used perspex (glass is relatively difficult to drill) with success. The keys to the clock running well are that; The teeth of the count wheel are clean and dry (it runs w

In fact it cannot ‘fall off’ because the K shaped bridge is ‘in the way’. Photo of a slightly earlier clock (which has been running for many years) attached. John

If you search eBay - there is an un-machined impulse pallet casting listed in the UK. (I am not and have no connection with the seller - nor have I ever seen or examined the part.) John

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