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Hornby APT 2020


PaulRhB
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2 minutes ago, phil-b259 said:

From Wikipedia (and I have no reason to doubt it)

 

Conventional capacitors provide less than 360 joules per kilogram of specific energy, whereas a conventional alkaline battery has a density of 590 kJ/kg. There is an intermediate solution: Supercapacitors

 

https://en.wikipedia.org/wiki/Supercapacitor

 

I therefore suspect that the capacitors used in the A class shown above (and similar) are not bog standard electrolytic capacitors as per the Hornby APT.

 

Don't believe everything on Wikipedia, in fact don't believe most of it. 

 

As @lyneuxposted above, there is a circuit using bog standard electrolytic capacitors giving 5 seconds of bright lighting and 30 seconds of some light. A capcitor will discharge quickly if allowed to, but if the delivered current is constrained, it will provide that charge over a period.


Roy

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  • RMweb Gold
2 minutes ago, phil-b259 said:

 

Depends on the circuit configuration - while LEDs don't pull much current things like limiting resistors can thus quickly depleting the cap. Also if the cap is the 'supply side' of any regulator chip then that may reduce its effectiveness.

 

Certainly that voltage regulator is having a bearing, and I suspect that is why there is no noticeable benefit from the capacitor. Modern quality SMD LEDs operate at about 1mA, so even were the capacitor delivery a very small current, the demand is equally small.


Roy

 

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19 minutes ago, WestRail642fan said:

i left my coaches on the track with full power for about 5-10 minutes, the capacitorb does work for 2-ish seconds after cutting power

 

That is more what I would expect from a 1000uF capacitor. I wonder why @PaulRhBgot no discernible benefit? Will test mine at the weekend, both on DC and DCC.

 

What I can't see on the boards is the resistance on the supply side of the capacitor. The time for a capacitor to fully charge is 5 x R x C. We know C is 0.001 but not what R is.

 

Roy

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7 minutes ago, AY Mod said:

Another consideration: the IRM capacitors only function on DCC. No one's got an APT driving vehicle yet to see if they perform better on DCC.

 

Why do we need a driving vehicle to see on DCC? I know you have something in mind, but I can't work out what.

 

Edit: Ok - worked it out!


Roy

Edited by Roy Langridge
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25 minutes ago, Roy Langridge said:

 

Don't believe everything on Wikipedia, in fact don't believe most of it. 

 

 

As the high-ups there won't let you correct blatant lies that are posted there, I'm not surprised in the slightest!  :nono:

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Just now, Mr_Tilt said:

 

As the high-ups there won't let you correct blatant lies that are posted there, I'm not surprised in the slightest!  :nono:

 

The trolls have more time and motivation than the maligned. There is no proper control when it's lies and libellous.

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Ok it wasn’t Mikes pic to share but there are three clips on the lower body moulding. 
 

Pressing in the lower body, not the upper window part. 
 

 

FAB7AFB6-D9C5-40EF-88B1-086C6E2A2470.jpeg.225bdd5b316c1de2e64e0a4f8c249259.jpeg

 

Edited by PaulRhB
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I did a quick test of my trailers on DCC earlier this afternoon. I'd say the lights last about a half a second after removing from the track. Hard to tell as the LEDs fade out gradually so hard to tell the difference between on and off once they get dim. Should be enough to smooth out any momentary interruption from dirty pickups though.

 

FWIW, the capacitors charge in a few seconds so no need to leave them on the track for ages to test. There are calculators out there on the web that tell you how long a cap takes to charge to supply voltage based on various factors.

 

Guy

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47 minutes ago, Roy Langridge said:

 

Don't believe everything on Wikipedia, in fact don't believe most of it. 

 

As @lyneuxposted above, there is a circuit using bog standard electrolytic capacitors giving 5 seconds of bright lighting and 30 seconds of some light. A capcitor will discharge quickly if allowed to, but if the delivered current is constrained, it will provide that charge over a period.


Roy

2 mins in to this video you can see the performance of the Hornby mk2e with the x11547 board, vs the Bachmann mk2f without the capacitor on DC.

 

 

Scroll to 2mins.. you can see the delay as DC fades out.

 

As a DC operator, I like it, it smoothes over bad rail joints and a slight delay. ive stripped around 30 coaches from ebay of this light fitting and re-used them on my stock, a relatively cost neutral exercise.
 

I’m moving towards CR2032 battery operateds though now.

Edited by adb968008
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3 minutes ago, Wolf27 said:

I remember when this topic was about the APT. Now it’s become an electronics thread. 

 

Still closer to topic than half the threads that wander off. At least we are trying to fix one of the apparent APT deficiencies.

 

9 minutes ago, PaulRhB said:

Pressing in the lower body, not the upper window part. 

 

Don't seem to get much inward movement on the lower part of my TRBS. I obviously need to be braver!


Roy

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4 minutes ago, Roy Langridge said:

 

Still closer to topic than half the threads that wander off. At least we are trying to fix one of the apparent APT deficiencies.

 

 

Don't seem to get much inward movement on the lower part of my TRBS. I obviously need to be braver!


Roy

Trying to fix a problem when we don’t have all the parts to see how it functions as a complete set. Im

happy to wait for the rest and let everyone else  about with theirs. 

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3 minutes ago, Wolf27 said:

Trying to fix a problem when we don’t have all the parts to see how it functions as a complete set. Im

happy to wait for the rest and let everyone else  about with theirs. 

 

Sorry, what has not having the full set got to do with a great big capacitor showing through the window? Also, given there are no interconnections between coaches, any flicker apparent now, will remain.


Roy

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10 minutes ago, Roy Langridge said:

Don't seem to get much inward movement on the lower part of my TRBS. I obviously need to be braver!

He’s asking how the other chap got in as I type, ;) 

I’m in the midst of paint and plaster on a board so not risking getting it splashed on the coaches :lol:

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2 minutes ago, Roy Langridge said:

 

Sorry, what has not having the full set got to do with a great big capacitor showing through the window? Also, given there are no interconnections between coaches, any flicker apparent now, will remain.


Roy

I don’t know, that’s why I’m not doing anything about it until I get the rest of the set. And hasn’t it been determined the component is to stop light flicker, not to act as a stay alive? Until I can run my set in anger I’m

not going to make any judgements on how parts may perform.

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30 minutes ago, Wolf27 said:

And hasn’t it been determined the component is to stop light flicker, not to act as a stay alive?

 

To an extent they are they same thing, you stop flicker by maintaining power to them (stay alive). As I run DCC I am not worried about lights staying on for a few seconds / at stations, what I do want is that they are not flickering on and off enroute. If, as some have reported, the lights go out immediately on loss of power, that will be an issue.


Anyhow, each to their own, some of us are choosing to look into it now, for the benefit of others. 

 

May we continue our electronics discussion now? ;)

 

Roy

Edited by Roy Langridge
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3 hours ago, Wolf27 said:

I remember when this topic was about the APT. Now it’s become an electronics thread. 

 

Could be worse, could be about bad cyclists......

Edited by newbryford
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2 hours ago, Roy Langridge said:

 

Don't believe everything on Wikipedia, in fact don't believe most of it. 

 

As @lyneuxposted above, there is a circuit using bog standard electrolytic capacitors giving 5 seconds of bright lighting and 30 seconds of some light. A capcitor will discharge quickly if allowed to, but if the delivered current is constrained, it will provide that charge over a period.


Roy

I have 1000uf caps fitted as stay alives in several diesels with sound and they last for fractions of seconds only, not even long enough to time TBH, but it’s enough to stop the occasional “sound reset” that used to happen occasionally on some points.

 

Other stay alives I have fitted are of the super cap type and those will run the loco for tens of seconds if lifted off the track, totally OTT really but they at least can be restricted to just a second or so if required.

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I am not a regular DCC user,  but a point comes to mind with say a 12 or 14 coach set.  On powering up the system would the DCC unit see the power inrush to charge up so many capacitors as a potential short circuit?  If the lighting boards were fitted with larger capacity capacitors would this not exacerbate the situation?

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Well, Hermes appear to have lost both my DCC chip and APT carriages, last 'updated' by Hermes on their tracker on 16th and 19th respectively.

And Hornby aren't replying to emails. 

 

This isn't terribly encouraging....

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31 minutes ago, GWR-fan said:

I am not a regular DCC user,  but a point comes to mind with say a 12 or 14 coach set.  On powering up the system would the DCC unit see the power inrush to charge up so many capacitors as a potential short circuit?  If the lighting boards were fitted with larger capacity capacitors would this not exacerbate the situation?

 

You have resistor fitted (R in my formula earlier) on the charge side of the circuit to limit the charge current of the capacitor. In theory, they should be set so as to not overburden whatever is providing the supply. The higher the resistance the lower the charging current but the longer the charge time.


Roy

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6D6D240C-491D-484C-A7C1-FF6EF82813D6.jpeg.764fd0217aa9ec52d09c248fe758c494.jpeg

 

…..or bad spellers 

 

@Erixtar1992 has put some pics and a video up on Twitter of the APT coaches stripped down and the capacitor, I’ve not got one on order but I’ve got to say I’m disappointed by the look of the white pantograph on it from the pic I’ve seen, was the real thing white? 
 

 

Edited by big jim
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