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Tyer No 7 tablet instruments

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Tyer No 7 tablet instruments

Unread postby David Holden » Tue Jul 26, 2016 9:30 am

Does anyone have any information on the bell and relay unit associated with these instruments.

This is the wiring diagram from the Tyer catalogue
Image

And an enlargement of the bell/relay bit
Image

The right hand relay is a polar relay which connects either of the two locks on the instrument to the battery. Also makes the bell circuit up regardless of polarity applied.

Any info on the relays used much appreciated. I will have to make something up as the chances of obtaining one (two) are going to be slim.
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Re: Tyer No 7 tablet instruments

Unread postby Chris Osment » Tue Jul 26, 2016 12:25 pm

I've been looking for one of those bells for years without success, so I'd be keen to learn the same info please. I have a suspicion that Tyer may have used the same equipment with the No 5 and also the 7A.
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Re: Tyer No 7 tablet instruments

Unread postby MRFS » Tue Jul 26, 2016 4:38 pm

Is there any reason why it shouldn't be different from a No 6 polar relay - 22ohms with a 12 ohm bell? They look very similar.

I can't find anything of much value in the LNE Scottish Area diagrams; but I have asked some NZGR contacts, to see if they can come up with anything. Failing that there's always Japan and South Africa to try.
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Re: Tyer No 7 tablet instruments

Unread postby John Webb » Tue Jul 26, 2016 4:39 pm

I'll try and see what we've got on the two Tyers we have at St Albans South tomorrow afternoon.
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Re: Tyer No 7 tablet instruments

Unread postby MRFS » Tue Jul 26, 2016 4:46 pm

Are they No 7s John?
ND: Why is there a door handle on the inside of my airing cupboard?
MF: Because it's the fire exit from Narnia.

I like David Lynch films. I don't consider incomprehension to be a barrier to enjoyment.
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Re: Tyer No 7 tablet instruments

Unread postby David Holden » Tue Jul 26, 2016 8:38 pm

Looking through the Tyer catalogue it would appear the same relay was used on the No 5 instruments, and there is even a picture.

Image

It does seem to function like those fitted to the No 6 tablet instruments.
Last edited by David Holden on Tue Jul 26, 2016 9:11 pm, edited 1 time in total.
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Re: Tyer No 7 tablet instruments

Unread postby John Webb » Tue Jul 26, 2016 9:07 pm

MRFS wrote:Are they No 7s John?

Sorry, I've rechecked and they are No. 6 machines.
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Re: Tyer No 7 tablet instruments

Unread postby Richard Pike » Wed Jul 27, 2016 6:25 am

A pair of PC105 930 relays with diodes in series with R1 arranged to make them a polar pair should do it. They are 20 ohms. Link the A1's and the A2's will be the other contacts. It may be that you have to butcher the D1+D2 contacts out completely and let off the return spring a bit to give you a bit of sensitivity.
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Re: Tyer No 7 tablet instruments

Unread postby David Holden » Wed Jul 27, 2016 7:25 am

Sounds like it's worth a try, Richard. Would need 4 relays obviously for 2 instruments.
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Re: Tyer No 7 tablet instruments

Unread postby MRFS » Wed Jul 27, 2016 10:58 am

One of my NZ contacts does have a diagram, and will scan it when he finds it.

Those coils look very typically Tyers, wrapped in their red embossed card. All things considered (and I know that the size of the coil is no indicator as to its value) I think that Tyers would have these sculling around their works in stock. The line loading and current usage would be about the same, I feel. The only thing that is different from a No 6 polar relay is the second set of contacts.
ND: Why is there a door handle on the inside of my airing cupboard?
MF: Because it's the fire exit from Narnia.

I like David Lynch films. I don't consider incomprehension to be a barrier to enjoyment.
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Re: Tyer No 7 tablet instruments

Unread postby Richard Pike » Wed Jul 27, 2016 11:37 am

David Holden wrote:Sounds like it's worth a try, Richard. Would need 4 relays obviously for 2 instruments.


I have some ideal ones in stock. They are AC immune and the slug may make them a little slow to pick. Worth a try though.
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Re: Tyer No 7 tablet instruments

Unread postby MRFS » Wed Jul 27, 2016 1:26 pm

More for Chris Osment than anyone else...

It appears that the ex-Chattenden and Upnor, then ex-Festiniog (conventional) No 5 instruments went to the Isle of Wight Steam Railway, with the bell units.
ND: Why is there a door handle on the inside of my airing cupboard?
MF: Because it's the fire exit from Narnia.

I like David Lynch films. I don't consider incomprehension to be a barrier to enjoyment.
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Re: Tyer No 7 tablet instruments

Unread postby Chris Osment » Wed Jul 27, 2016 6:41 pm

MRFS wrote:More for Chris Osment than anyone else...

It appears that the ex-Chattenden and Upnor, then ex-Festiniog (conventional) No 5 instruments went to the Isle of Wight Steam Railway, with the bell units.

Thanks for the info, but what are the IoWSR doing with them? In their museum, as I assume not in traffic use? I doubt they would want to part with a bell unit though....:-(

Nice catalogue picture from David !
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Re: Tyer No 7 tablet instruments

Unread postby MRFS » Thu Jul 28, 2016 8:14 am

I have now had sight of the Waipukurau - Otane - Opapa section (switchout at Otane) and it's nice to have a hunch vindicated, the bell unit relays are 22ohm. :)
ND: Why is there a door handle on the inside of my airing cupboard?
MF: Because it's the fire exit from Narnia.

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