Couple of questions about plug-in relays

[Paul_C]

and that's not to mention the vast amount of electromechanical stuff which was in telephone exchanges - up to the '60s, at least, until 'System X' was phased in.

System X started to come into service a little over 30 years ago. TXE (electronically controlled) systems started to be installed during the 1960's onward, but still using large numbers of reed relays for switching.

The last electromechanical (Strowger SxS) exchanges in the British network weren't withdrawn from service until the mid 1990's.

 

[JohnW2]

and that's not to mention the vast amount of electromechanical stuff which was in telephone exchanges - up to the '60s, at least, until 'System X' was phased in.

System X started to come into service a little over 30 years ago. TXE (electronically controlled) systems started to be installed during the 1960's onward, but still using large numbers of reed relays for switching. The last electromechanical (Strowger SxS) exchanges in the British network weren't withdrawn from service until the mid 1990's.

Thanks for clarifyng the chronology; for "the 60s, at least", please read "the late 70s"

I seem to recall that there was a heated debate which went on for many years, starting around the mid-60s (when I was a teenager, playing with electronics!), about whether the UK should go with System X or an alternative, the name/nature of which I can't remember. Harping back to the comments about computers, when I was in the 6th form, we successfully produced an electromechanical 'binary adder', of which we were very proud!

Kind Regards, John.

 

[bernardgreen]

In the 1960's there were invoicing machines that used convertors built using relays that converted £ s d ( Pounds shillings and pence ) into either pence or fractions of a pound so the amount could be entered into a standard mechanical calculator for the invoice calculation. The result was then converted back into £ s d for printing in the invoice.

Solenoids were used to press the buttons on the calculator and the print out mechanism was replaced with an electrical readout system.

From memory there were over 60 relays, many had 10 or more changeover contacts and some could have as many as 20. The contacts had to be physically very small. The moving contacts were gold plated straight wire springs about a millimeter in diameter and about 30 mm long. The fixed contacts were about 3 mm apart.

To prolong the life of the contacts none of them actually switched current. The route through them was set up by operating the necesary routing relays first and then a more robust relay connected voltage to one end of the route and depending on the route set up one or more output relay coils were fed with current and these operated. These ouput relays latched on via a second coil and then the voltage was removed from the route before the routing relays were de-energised to prevent any arcing as their contacts opened.


For the young ones here £ s d was not decimal....

12 pennies made a shilling
20 shillings made pound
240 pennies to a pound.
4 farthings made a penny

£ or L was used for pounds from the Latin ( or French ) Livre = pound
d was used for pennies from the Latin Dinario

 

[Stoday]

The only place you could spend a farthing was the baker's, where a small loaf cost 2¾d in the late 1940's.

 

[bernardgreen]

Did you never enjoy a Black Jack sweet, farthing each or five for a penny. ( or maybe 9 for tuppence ) The old lady who owned the sweet shop was ahead of her time in sales techniques and I recall we would club together to bulk buy to get the discounts. ( Old ? she was probably only 30 to 40 but to us in the 1950's she was ancient in age )

 

[Paul_C]

I seem to recall that there was a heated debate which went on for many years, starting around the mid-60s (when I was a teenager, playing with electronics!), about whether the UK should go with System X or an alternative, the name/nature of which I can't remember.

If you're thinking about something specifically as a "rival" to System X as such, then you might be thinking of the debate in the early 1980's about whether to put all the eggs in one basket, so to speak, of adopting System X as the sole system for future installations (it being a co-development between the Post Office, Plessey, GEC, and STC). It was the decision to introduce an alternative system from a different supplier which led to the additional widespread adoption of Ericsson's AXE10 (a.k.a. System Y) throughout the network.

But there has always been debate about which system to adopt, ever since telephony took off, such as the decision in the early days of the G.P.O. monopoly to adopt the Strowger SxS system as the basis for operations throughout the British network, over alternatives which existed at the time (e.g. the rotary system which became common in parts of Europe).

 

[JohnW2]

If you're thinking about something specifically as a "rival" to System X as such, then you might be thinking of the debate in the early 1980's about whether to put all the eggs in one basket, so to speak, of adopting System X as the sole system for future installations (it being a co-development between the Post Office, Plessey, GEC, and STC). It was the decision to introduce an alternative system from a different supplier which led to the additional widespread adoption of Ericsson's AXE10 (a.k.a. System Y) throughout the network.

Hmmm - I'm sure that the debate I'm vaguely recalling started much earlier than the early 80's - I was pretty sure it was mid/late 60's, but it could have been early 70s, but I suppose I could be wrong.

Totally different, but I also recall reading the extensive debates (in 'Wireless World', amongst other places, if I recall) about what system the UK should adopt for car and mobile ('hand portable') phones. Just to prove how wrong I can be, I can remember feeling that the 'cellular network' approach would be completely unworkable; I can't recall what the alternatives were, but I presume they must have involved much higher power transmitting capabilities of the handsets.

Kind Regards, John.

 

[ricicle]

Has Harry not heard of PLCs then ?