Re: Impulse Driver

John Hubert

OK, thanks.

The standard Synchronome type (as Bob Miles book) doesn’t have a relay ‘between' the master and the board.  I use an emitter follower (removable without trace) to limit the master contact current to the usual 300-350 mA with my 6 channel Synchronome board.

Gents boards I have seen work in a ‘conventional’ really form with the relay coils (one for each circuit) in series driven by the master, and each relay contact set acting as the ’switch’ in independent circuits.


On 22 Mar 2021, at 10:27, Peter Torry via <peter.torry@...> wrote:

Hi John,

Yes, I think that they are all much of a muchness and differ only in the circuitry employed.  This example has a medium size relay as the interface between master and distribution outputs plus some spark suppression components.


On 22/03/2021 09:34, John Hubert wrote:
Hi Peter,

That looks very similar to the Synchronome type.


On 22 Mar 2021, at 09:27, Peter Torry via <peter.torry@...> wrote:

Good morning all,

Following your request I attach an image of a six circuit Gillet and Johnston distribution system for your information.  The jack plug stored at the top of the unit can be removed and inserted in any of the other circuits to display that circuit current on the meter and the rheost adjusted to give the required current in that circuit.  To advance a particular circuit the toggle switch is moved from normal to advance and the push button next to the meter depressed as required to bring the circuit to time.

Kind regards

Peter  UK

On 22/03/2021 06:52, Simon Taylor wrote:

With GPO clocks, you have a GMT relay set so that you can power several clock circuits in large buildings.

With Synchronome, you have a distribution board, which does the same thing. It just allows expansion so that a really huge enterprise can run hundreds of clocks. From memory, County Hall in London was fitted out by Gillet & Johnston and had 1200 clocks running in it.

I would have loved to see the distribution system used there!

Simon GPO Clocks


Join to automatically receive all group messages.