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Old 9th Nov 2017, 2:08 pm   #21
russell_w_b
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Default Re: Hotel Panel Radios

Synchronised, possibly? Before November 23 1978 it was BBC Radio 2 that went out on 200kHz Long-Wave from Droitwich. Radio 4 after that date. So might 200kHz have been used as a frequency standard to keep the clock disciplined?
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Old 9th Nov 2017, 2:18 pm   #22
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Default Re: Hotel Panel Radios

Doesn't / didn't Droitwich LW carry a signal used in connection with Economy 7 and similar electricity tariffs? Perhaps the clock somehow used that to synchronise twice a day?
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Old 9th Nov 2017, 3:07 pm   #23
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Default Re: Hotel Panel Radios

The clock was powered from the Radio 2 signal simply by rectifying it and using the DC to power the clock. The very low power demands of the clock made this possible.
Radio 2 was chosen because, back in the day, it was the only station to broadcast 24hours a day!
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Old 9th Nov 2017, 3:22 pm   #24
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Default Re: Hotel Panel Radios

Quote:
Originally Posted by Dai Corner View Post

Doesn't / didn't Droitwich LW carry a signal used in connection with Economy 7 and similar electricity tariffs?
Yes. 22.5 degree bi-phase modulation of the carrier, including clock data.
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Old 9th Nov 2017, 3:26 pm   #25
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Default Re: Hotel Panel Radios

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Originally Posted by Bob_Moss View Post
The clock was powered from the Radio 2 signal simply by rectifying it and using the DC to power the clock.
Surely you mean rectifying the stepped-down 100V audio line input to the hotel room unit? Transferring the electricity originally derived from the mains downstairs, converted to audio and sent to the hotel room clock up the PA distribution wiring?

I can't see the BBC being so generous as to provide sufficient field strength to overcome a diode voltage drop for the abstraction of free electricity!
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Old 9th Nov 2017, 3:32 pm   #26
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Default Re: Hotel Panel Radios

Sorry, should have been clearer. All the radio feeds to the bedhead unit were at AF, using telephone twisted pairs. The multiple Tuner/Amplifier was somewhere in the lobby in an inaccessible cupboard normally.
100V line was used for the hotel PA, but not for the audio to the bedhead units, due to having to use multiple step-down transformers and the undesireability of having 100v near the customer.
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Old 9th Nov 2017, 3:48 pm   #27
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Originally Posted by Bob_Moss View Post
100V line was used for the hotel PA, but not for the audio to the bedhead units, due to having to use multiple step-down transformers and the undesireability of having 100v near the customer.
Thanks for that, Bob - interesting stuff. I was about to get onto the patents office there! I guess, like rediffusion TV and radio, it was 'of its time' and has been superseded by a flat-screen telly in even the cheapest hotel room.

I have stayed in several hotels recently that have PA speakers in the ceiling: never heard anything from them, though.
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Old 9th Nov 2017, 5:06 pm   #28
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Default Re: Hotel Panel Radios

Hotel radios always make me think of Carry on Abroad
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Old 9th Nov 2017, 5:39 pm   #29
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Default Re: Hotel Panel Radios

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Hotel radios always make me think of Carry on Abroad
Nice 1968 Ericsson Dialog telephone there. Got one of those! Same colour as well. Swedish instrument used on PAX systems (where mine came from) and Egyptian telecoms network, amongst others.
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Old 9th Nov 2017, 7:29 pm   #30
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Default Re: Hotel Panel Radios

Apologies Russell, In my neck of the woods you can power small stuff such as LCD clocks from 909kHz if you are determined enough.
Once it was R4 then R2 now R5.

I used to use crystal earpiece OA81 and 33k resistor to the nearest metal object back in the day for the Archers.
Now lost it's appeal. Front door knob worked well.

I'm pleased I live no closer to BPK.

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Old 9th Nov 2017, 8:21 pm   #31
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Default Re: Hotel Panel Radios

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Originally Posted by Jon_G4MDC View Post
Apologies Russell, In my neck of the woods you can power small stuff such as LCD clocks from 909kHz if you are determined enough.
That sort of thing happened at Droitwich many years ago too.
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Old 13th Nov 2017, 4:36 pm   #32
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Default Re: Hotel Panel Radios

I used to work for The Rank Organistion, in the Top Rank Television division.

I used to install these systems, amongst other things.
We had an engineering agreement with Rediffusion, and used a similar system to them, but on different frequencies for TV distribution in hotels.

As well as distributing the TV signals at what was known as 'System Frequency', the audio was carried on the same pairs as the RF, at a nominal 50v.

This works the same as tradititional 100v line audio distribution, but the lower level was used so as not to cook the vision inserts.(Attenuators/ filter chokes etc).

We fitted Bed-head panels, some with TV & some with only radio.

The unit was simply a selector switch system, accessing each audio /vision pair. This was then fed to the bed-head speaker, or TV speaker, which incorporated a 50v line matching transformer. There were often local 'In-house' generated audio programmes, as well as TV replayed from banks of U-Matic recorders.

We used to fit these all over the world, as well as hotels in the U.K.

David.

Last edited by Vintage Engr; 13th Nov 2017 at 4:37 pm. Reason: Typo.
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Old 17th Nov 2017, 9:48 pm   #33
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Default Re: Hotel Panel Radios

A company called Sound Diffusion had a system in a local hotel in the 50's, two radio chassis Home and Light programmes feeding units in the bedrooms.
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Old 18th Nov 2017, 11:44 am   #34
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Default Re: Hotel Panel Radios

Attached are photos of the system I built to enable me to lisen to British radio here in the south west of France.

The system comprises a quattro LNB on the dish feeding a 16 outlet distribution amplifier. This feeds five satellite receivers (only four in the picture;one is faulty). These feed a home built five-channel power amplifier.

The signals are fed at 100 volts using telephone twisted pair to speaker units (the one shown is in my bedroom along with my work boots). The receivers run continually but the power amp is switched on by a DC phantom across the speaker feeds. When a station is selected, a DC path to earth is formed which operates a relay to power the amplifiers. The satellite dish also feeds televisions in various rooms.
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Old 30th Dec 2017, 11:10 pm   #35
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Default Re: Hotel Panel Radios

This thread reminds me of the 'radio' installed at our primary school in Leeds. The school itself was built circa 1950 and the radio consisted of (externally, at least) a ceiling-mounted loudspeaker grille in each classroom (several in the hall) with a simple toggle switch for on/off. There was no obvious volume control, tuning or station selection. As I recall, all we ever heard was the Radio 4 Schools Service which was probably on LW as this was 1975 through to 1980. So I don't know if there was a genuine radio receiver in the school, a Rediffusion-style cable system or a Leeds City Council network using GPO lines. Interesting times.
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