Original Metropolitan Official Handbook from...... 1963 !!!

[hb88banzai]

Here's a picture of what the last type of relay used on both Met Boxes and Posts looked like -



and inside -



The lower section is the solenoid that is activated by the normal ringing signal sent on the phone lines from the Station (the same type of signal sent on home phones, but at a different frequency). When activated it mechanically moves the mercury switch in the top (high voltage) section that makes the connection between the electrical mains and the top light (and the parallel inside blue lamp). The bell is just rung off of the original signal itself once separated out by the Network (usually separate from the phones of the period).

Here's the bell in the Post at Avoncroft -



And here is the electrical section showing the relay -



And finally here is the rather untidy main electrical board on the Crich Police Box (you can just see the bottom of the desk drawer at the top of the picture) -



Note that per the GPO plans covering the PA 350 system some of these bits and pieces (those having to do with phone signal conversion and routing) were originally mounted under and around the phone cupboard rather than here on the electrical board. Those plans only showed the (somewhat larger old model) relay and the 250 V AC/15 amp dual-pole switchable power splitter box (and fuse) mounted here.

All the above pics are either from starcross or Mark (who hasn't posted for awhile).


EDIT: One final note about the ringing frequency - though the final ringing signal for the Police Exchange systems was at 50 Hz, which is double the British domestic ringing frequency of 25 Hz (20 Hz in the USA), the final effect would be roughly the same since the GPO bell used in the Police system is a single bell sounding once per cycle while the domestic phones and bell sets used two bells with a single cycle of the clapper ringing both of them once (one each on the down and return stoke). The net effect is the same number of audible bell rings per second. The main difference is in the size of the bells in that the Police system used the single bell of somewhere between 4" and 6" diameter, while the small bells used elsewhere were only around 1.5" to 2" in diameter (usually tuned separately). So the sound from a Police Box or Post should be not only louder, but also somewhat lower in pitch (and without the multi-tone tinkling sound typical of home sets).

The earlier 17 Hz signal, however, is a whole different matter. I'd love to get my hands on one of those bells and record some clean test samples at the different frequencies and with the correct on-off cadences.


Addendum:

As a point of comparison, here is the Electrical Board for the Glasgow Police Box at Avoncroft (also attached to the wall under the table and drawer - also courtesy of starcross) -



Note that it has been kept much more organized than Crich, and with most of the wiring being routed safely behind the board. It also appears the internal lights are on a timer so they come on automatically around dusk.


And here is a picture of the applicable area in those 1937 plans from the GPO for the new PA350 system -



The relay is the unmarked rectangle at the top of the teak board.

Here is a top view of that same section showing the info on the relay (again, as per 1937 specs)-

[hb88banzai]

Doing some basic photo-analysis, the Avoncroft Police Post has a 4" bell, while the Crich Police Box has a 6" bell.

Here is the only picture I've been able to find of the Crich bell -




On the Glasgow boxes (judging from the one at Avoncroft), if the lens is 6" in diameter then the bell "cap" on top of it appears to be 8".

[jamesb]

Great information.

[hb88banzai]

I note that the Avoncroft Police Post's bell is labeled as being rated at 240 V. AC, so it would not be running off of the actual ringing voltage (which is more like 40-90 V. under load). Most likely it is connected in parallel to the same relay as the signal lamp, and since the mains in the UK also operate at 50 Hz that would match the later signaling specs. It's quite possible the same setup was used in the Police Boxes (both Met and Glasgow Beacon Bell types) from at least the PA 350 System on. Anyone know if there's a label on the Crich bell?

It's interesting that in the separate GPO layout plans for the then new PA 350 System Police Boxes and Post No. 2's (plans both dated 1937) no provision is shown for a Bell or its conduit where you would expect to see them (back wall on the Met Box and behind the phone in the No. 2 Post), despite the bell signaling being described in the documentation for the PA systems all the way back to the PA 101. In the documentation for the PA 450 System (dated 1958 and reiterated in revisions from 1963) it is specified that if an internal bell is desired in a Kiosk (ie, a Police Box) then a Bell No. 64D should be mounted - which is a much smaller two-bell ringer with only 2.5" bells. Here's a pic -



I should think that this would be connected to normal phone signaling voltage and frequency (25 Hz, as with a Bellset), however, because otherwise with two bells the effective ringing frequency would be 100 Hz and sound more like a really sharp, loud buzz (if it worked at all since these types of bells have resonant circuits designed to operate within a fairly narrow range of frequencies). I don't have operational specs on a 64D, so I'm not sure. What little info I do have seems to suggest it is normally connected to phone lines directly as if it was just another telephone.


In the previously posted picture of the Avoncroft electrical board, btw, the black box at the upper left corner of the board is a GPO Bellset - probably a No. 26. As the top Beacon Cap Bell has been described elsewhere as having been disconnected (no longer having a solenoid), this is undoubtedly what is heard when the box is called.

The long white thing up top with the "Danger 240 Volts" is probably the relay for the lights, and the black rectangular (Bakelite) boxes flanking them appear to be GPO No. 20 Block Terminals (the long ones 8 pair and the smaller ones 4 pair) for telephone connections and local distribution (IIRC, there are, or were, two phones installed in the Avoncroft box). The longer No. 20/8 is precisely the same type specified to be attached to the front door side of the phone cupboard on Met Police Boxes in the 1937 GPO plans.

The grey box on the lower left is a GPO unit that is probably a master phone distribution Connection Box (like the punch-down panel outside a home) - possibly a No. 1B.

The black box with the blue stripe is a master power splitter box with on/off switch and fuses (equivalent to the "MEM" unit on the Crich panel).

Attached to the pillar adjacent to the board are two mains voltage (240 VAC, 50 Hz) electrical boxes - the top one with a power outlet (not sure what the round thing is on the electrical board that is plugged in here) and the bottom one with a switch for the heater unit, which is those two tubes partially visible on the adjacent (rear) wall to which the switch is attached via separate cable. This last appears to be closer to how things are laid out in the GPO plans than what the current setup is at Crich, but that panel is quite a mess in comparison.

[hb88banzai]

Back a bit more on topic -

While the find and info is quite fascinating and really great to see, it strikes me as strange that there is so much information missing from this handbook regarding the the day-to-day operation of the Police Boxes (or the Posts for that matter).

They seem to very much gloss over any specifics of operation in favor of a brief description of their general function and use. Nothing about testing the signaling equipment using the button, turning the lights on at night nor the use of the heater - nothing about the location of the first aid kit or the fire extinguisher - nothing about cleaning it, the need for ventilation using the windows, or even the proper way of locking it (if it's the type of lock I think it is, it would be a half turn of the key opposite of the opening direction to deadlock it so as to be more secure than just latching it). They don't even mention that you can access the phone from inside or that there's a lockable drawer for the log book, much less talk about any procedures for detaining prisoners while awaiting transport, etc.

Just seems a bit odd when this is all information any Beat Officer would need to know.

[Teletran]

Most of that would be done by regular officers as opposed to special constables, as noted in the text these would not carry keys to the box.

[jasononion]

Back a bit more on topic -

While the find and info is quite fascinating and really great to see, it strikes me as strange that there is so much information missing from this handbook regarding the the day-to-day operation of the Police Boxes (or the Posts for that matter).

[jasononion]

I'll have a rifle tonight for additional information in the book.
Also, I have now accquired a original Police and Post Box key which I will post later.

Onion

[whitestar2010]

I might have some more info in my version of the Police Box System Guide - may or may not be the same version though. Hope the link works ok for everybody.



http://www.mediafire.com/?3v4gcc8yxjogp

[deck5]

Thank you for those scans.  Are File0003.jpg and File004.jpg missing on purpose?

[whitestar2010]

So sorry, yes file 4 was missing - have fixed now I think. All complete now - no file 3 just a mix up with my scanning.

[deck5]

All complete now - no file 3 just a mix up with my scanning.

Thanks again!

[jasononion]

Happy happy joy joy happy happy.
This is all good

(its just dawned on me, I'm a train spotter about the TARDIS)!

COOL! lol

[hb88banzai]

whitestar2010 -

Those are wonderful! Many, many, many thanks for these!


Teletran -

Of course! (sound of hand slapping head)

The significance of "Special Constabulary" had completely escaped me. Thanks for the observation.

[hb88banzai]

In reading some of the details, I think the Holy Grail might be an Engineer's Manual for these things, as the City Engineers seem to have been responsible for their upkeep (and perhaps installation), plus maybe a GPO manual that covers their portion of the installation and maintenance.