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Old 7th Jan 2010, 12:39 pm   #35
beery's Avatar
Join Date: Jun 2006
Location: Ware, Hertfordshire, UK.
Posts: 739
Default Re: 'Button A-B' and grey payphones.

Hi All,
whilst I can't actually answer the question directly I can point out that the change over of any particular coin box occured when the local manual exchange went automatic or the automatic exchange was replaced/enlarged.

However, even after the country became entirely STD in 1979 there still may have been AB boxes around, but it would have meant having to have a central suite of operators to time the STD calls. Does anyone know if this happened?

Btw I have a working AB box. It is very well made, but mine had a refund chute that had been bent with a crow bar. It did not help access to the money though. I had to have the spot welds re-made.
The post payment box uses a dial-type mechanism driven by a weight which was raised by putting a coin. Essentually the 5p being smaller in diameter raised the weight to a lower height than the 10p. The only reason for having the two separate coin slots was to measure that the diameter of the 5 and 10p coins were within tollerence.
The weight would drop back, regulated by a govenor and would dial a number of earth pulses which would tell the exchange the amount paid.

Also, if you remember there was a lock on the coin slot, which opened upon the line current reversal which happened when your call was answered - time to put the money in.
Then, as you time ran out, do you remember the pips? A very faint memory for me. I assuming they were based on the flicker earth from the exchange, 0.2 sec on, 0.2 sec off. I will have to recreate it on my own exchange.


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