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Hornby Dublo 3 Rail track with fitted electronic component.

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P&P

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I have a standard full length piece of Hornby Dublo 3 rail track, which has the two screw power terminals (+ & -) fitted.

On the underside of the track is an electronic plate which is connected to one of the power terminals at one end of the plate and connected to one of the outside rails from the other end of the plate. The plate is a darkish yellow with the following alpha numerics printed on, all in Upper case.

9C1SMP
TCC
4700PF + 20%
(The plus and minus are printed one above the other)

Imediiately above the capital letters 'PF' in much smaller print are the letters ZO, it is possible, that they are meant to be read sideways, in which case, the Z becomes an N followed by O.

The whole plate and wiring is covered by a hard stiff silicon plate of the type used for circuit boards, and very tightly wedged, between the two down sides of the supporting base plate holding the track.

Obviously it is a power rail from the Controller, but I have numerous power rails on my railway circuits, but not one has this component.

I have never seen it in any Hornby train/product catalogue from the 1940's, 50's or 60's, nor in any Toyshop selling Hornby during this era.

Can anyone help as to what this component is for, what it does and / or how this piece of rail track is intended to be used?
 
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Cowley

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I have a standard full length piece of Hornby Dublo 3 rail track, which has the two screw power terminals (+ & -) fitted.

On the underside of the track is an electronic plate which is connected to one of the power terminals at one end of the plate and connected to one of the outside rails from the other end of the plate. The plate is a darkish yellow with the following alpha numerics printed on, all in Upper case.

9C1SMP
TCC
4700PF + 20%
(The plus and minus are printed one above the other)

Imediiately above the capital letters 'PF' in much smaller print are the letters ZO, it is possible, that they are meant to be read sideways, in which case, the Z becomes an N followed by O.

The whole plate and wiring is covered by a hard stiff silicon plate of the type used for circuit boards, and very tightly wedged, between the two down sides of the supporting base plate holding the track.

Obviously it is a power rail from the Controller, but I have numerous power rails on my railway circuits, but not one has this component.

I have never seen it in any Hornby train/product catalogue from the 1940's, 50's or 60's, nor in any Toyshop selling Hornby during this era.

Can anyone help as to what this component is for, what it does and / or how this piece of rail track is intended to be used?
Would you be able to post a couple of photos of it P&P?
 

AM9

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It's a 4700 picofarad capacitor. It was probably added as an interference suppressor to reduce the probability of arcing at the centre rail contact from producing radio and or tv interference. Remember that both of those were analogue systems and very susceptible to interference.
 

P&P

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It's a 4700 picofarad capacitor. It was probably added as an interference suppressor to reduce the probability of arcing at the centre rail contact from producing radio and or tv interference. Remember that both of those were analogue systems and very susceptible to interference.

Thank you that is very helpfull. Other Hornby owners I have asked were also at a complete loss. So I can now pass on the info.
 

P&P

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krus_aragon

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Thank you that is very helpfull. Other Hornby owners I have asked were also at a complete loss. So I can now pass on the info.

I assume they were not fitted by Hornby, but by and eloctronics specialist, after purchase (Radio/T.V. repairer) ?
The fact that the yellow enamel(?) paint covers the rivets implies that the capacitor was manufactured and sold with the wires attached. I've not seen a capacitor of this design before, most have wires that go into the packaging, or bare metal lugs for attaching wires. (I've seem little that's older than the 60s, though.)

TCC appears to be the name of the capacitor's manufacturer (the Telegraph Condenser Company), they merged in the 1960s and ended up being part of Plessey by 1965. ("Condenser" is an old term for a capacitor.)

Incidentally, 20% tolerance on a capacitor is very slack by today's standards. But it's good enough for the job required.

As to whether it was retrofitted to the track after manufacture, I couldn't guess at that without a close look at how the capacitor's been connected to the rails.
 

AM9

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they are for suppressing tv interference you get them on motors as well
they will work fine without them
https://picclick.co.uk/Triang-Hornby-class-31-37-working-power-352555021796.html
Don't be so sure that motors will work fine without them. Not only do they reduce rf interference, - they also quench some of the arcing at contacts like the brushes/commutator interface on DC motors as used in model locos. That's why those motors have a capacitor (and inductor) mounted across and in series with the motor respectively.
 

AM9

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always kept my commutators and brushes perfectly lean and spotless :D
But there will still be back emf spikes that should be quenched both for emi suppression and (ultimately) long-term damage to brushes and commutator segments.
 

John Webb

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"Hornby Dublo Trains" by Michael Foster (New Cavendish Hornby Companion Series, published 1980 and 2nd Ed. 1991) says that suppressors were fitted both to track and locos at the factory from 1950 onwards.

This followed co-operative work with the Post Office Engineering Department after, in particular, the BBC restarted TV services following WW2 which were found very susceptible to interference.
 
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