Times change

In message , Harry Bloomfield writes

You have to wonder who determines these specifications..

As a sprog apprentice, I was sent out to an American air force installation near London to supervise test runs on a DC motor generator set.

The spec. called for the set to take over the load (comms of some sort) within 10mS! of the mains supply failing.

Needless to say 10mS could not be achieved. Simple reactance calculations of the motor field winding would have shown this.

The cure was a thumping great flywheel.....

That's what was used in a telephone exchange I visited in the 1950s.

charles presented the following explanation :

This was three motors, driving three big pump sets, pumping from a reservoir, all remotely monitored and controlled by telemetry from the other side of a city.

I did a similar thing with a new fangled device called a hall effect sensor and a magnet glued to the spindle grin.

Not very imaginative and in those days simple pulse counters were el cheapo. Brian

Back in the early 1970's I worked on the control computer (Ferranti Argus

I had engineers who refused to visit the place as the girls on the paper cutting line were definitely not 'PC' and were known to literally remove visiting engineers trousers :) Talk about sexual harassment - it wasn't only the paper making process that made for a hot and steamy atmosphere !

Andrew

Tee-hee. As a student in the early 70's, during vacations I worked in WD & HO Wills tobacco factory (now a shopping centre) in Bedminster, Bristol. There were parts of the factory that some men were nervous about entering for the same reason!

ObDIY; I mostly worked as a fitter's mate. Great times.

Several members of my family worked there in the 70s, apparently the work's outings were legendary :)

Of course it's all gone and turned into housing now.

Lee explained on 17/08/2017 :

What was really appreciated by me, was the fact that all of that work I did back then, will still be there and very much still in full use.

Brian Gaff formulated the question :

From what I remember, I used a proper crystal controlled counter timer circuit, interfaced to an LED display and a combined IR transmitter / receiver module. With the latter bolted on a bit of broom rod, so the shaft could be reached. It focused over just a few inches, so had to be close.

Shaft was polished with a bit of emery, then a bit of black tape added to create the pulse.

In message , Harry Bloomfield writes

Well the Clywedog reservoir dam is still standing. Now you have reminded me, I wonder how the Germanium transistors fitted in the control gear are holding up!