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Lane Change

12K views 33 replies 14 participants last post by  dutchdog 
#1 · (Edited by Moderator)
So moving on to the lane Change. I know some of this has been covered in darainbow's Carerra Hybrid thread, but will leave that now to his conversion progress reports.

So first a look at the circuit board.



Working Round.

Power from the rails.
Input from the deadstrip.
Comparator. I would have thought they could have fed the signal straight to to the Microcontroller A-D. Obviously some additional signal conditioning was needed.
I had first assumed this would be the 5V regulator. The 5V must come from somewhere else? Perhaps one of the diodes.
Atmel tiny26L, same as the in-car controller. J4 is again in circuit serial programming.
Finally the solenoid drive circuitry, Diode to protect against back EMF and a 3NF06L Mosfet. Quite beefy with 4 Amp continuous drive.

I decided to measure the current taken by the board on a lane change. I do not expect this to be the problem it is with SSD as the LC's are only operated when a car wants to change lanes as opposed to every time the sensor is crossed.



Here's the trace measured across a 0.1 ohm resistor. Not sure why it's so noisy. Perhaps thats why they have added the LM393 comparator.

The pulse length is as has been described. Dependant on car speed. It varies from 25mS to 200ms.
This one is a 200mS pulse, pushing the car through quite slowly. There will be a minimum speed these work at, but you will probably have stalled on the dead strip by then.


Not sure how they measure the speed. Could either be time on the deadstrip, or determined by how many ident bursts are received.

So the maths are 2 Amps for 0.2 second worst case. It is easily possible that 2 cars could cross lane changers simultaneously so perhaps 4 Amps which is significant, however as the time is 200mS worst case I do not think it will be a problem. Lessons have been learnt.


Finally I think worth repeating these notes on analogue usage.

QUOTE (RichG @ 9 Dec 2006, 10:49) <{POST_SNAPBACK}>It looks very clear that Ninco like Scaley have bussed the tracks across in the Lane Changers to improve the power distribution.

Now I know Ninco Bob has on SCI said.
QUOTE But you MUST use the NINCO 10401 Double Power Power Base (the "Blue" one... the one that uses 2 separate power supplies) rather than the standard 10101 Powerbase that comes with every analog set, because each lane of the N-Digital lane change track sections must be independently powered when used in an analog layout.
I think as ever he is looking through his Rose Tinted Glasses.
It doesn't matter if you have one PSU or two, if the rails are joined you ain't gona have control of two cars.



So this wire will need removing, track should still be fine in Digital mode, assuming the lanes are bridged in the Powerbase track. All the other Digital specific tracks will also need checking. Pit Lane, Control Tower, Multi Lane and Digital sensor tracks.


Rich
 
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#2 ·
Can't help thinking that the high current demand (both here and on SSD) is dictated by size limitation - the solenoid has to fit within standard track height

Mine are much beefier (made in the UK for RS
) and draw just 0.25 A

Something worth considering for a routed track

Beppe
 
#4 ·
Absorbing reading as usual Rich, I really enjoy your in depth investigations, although I have no interest in switching to Digital in any form.

One point regarding the dead sections that seem to be problematical on Ninco Digital; could not the problem be overcome with a "live frog" type solution as found on model railways to prevent stalling on points at very low speeds?....I don't know if this is feasible with the Ninco system but it certainly works on Peco.....


Keep up your pioneering work, you never know one day one of the Manufacturers may come up with a system to rival analogue.......


Regards (In admiration)

Alan
 
#5 ·
At last, Rich has ninco... pity they never tempted him to come to spain to work for them in Barcelona on R+D:
a) we would have had it earlier
with all the bells & whistles(including an interface... and something to chase the cat from the track
c) we would also have somebody to moan at ;-) if it ever (dare) go wrong

Nice work Rich, Thanks a ton

Regards
Robert
 
#6 · (Edited by Moderator)
Rich you have make much progress in investigating N-Digital. keep up the good work!

On what you've have discovered this far, do you think it will be possible to convert a Scalextric track (with SSD LC's) to N-Digital? Or can't you give a good answer on this question in such an early stage in your research work.

derregenbogen did a good job on converting Pro-x.
 
#7 · (Edited by Moderator)
My answer is as always, anything is possible.
Have not thought about it much. You would need to scrap a N-Digital changer to do it. A pair of LC's about £26.

You would need to create a dead strip by cutting the track as in derregenbogen's thread, this would need to be in the adjacent track piece for the CLC's. The Scaley solenoid would probably be fine, just leaving you to fit a return spring in place of the second solenoid. The PCB is quite small so could probably be made to fit. So I think highly possible, someone would need to do one to confirm the detail.

Rich
 
#8 ·
Hey Rich looking at the photo of the wire jump and where its located, just up and to the left is an open space, looking at the track side should be red/white painted lines, couldn't you just put a switch in there, accessible from the top, one side designated for analog, wich cuts the wire -flip the switch to connect for Digital. This could have been or could be done to all lane changers cheaply, and would have given them (Ninco) thier digital/analog conversion.

? you only have to put a switch on one wire right? posotive wire or negative

Johnny Mac
 
#9 ·
Hi Johnny

No need for the switch, just remove the wire. It will still work fine in digital mode as the tracks are connected in the Digital Powerbase, which of course you remove when you convert to Analogue.


Rich
 
#11 · (Edited by Moderator)
I wish I have read this thread before I attempted the analogue conversion... I left the LC's in!
So, yes, I've confirmed what has been said here... sigh! - And one of my LC's went south (don't know which component, but something got toasted).

Johnny Mac, are you thinking that they did it to better equalize the rails? (perhaps assuming that LC's are most likely evenly spread out throughout the circuit)... I'm wondering if anyone has noticed any degradation in performance after taking the rail jumpers out?

Thanks for the insightful information (I'll be sure to look here next time)
HookEm
 
#12 · (Edited by Moderator)
Well, removing that one jumper on the photo ("Remove For Analogue") does not completely isolate the lanes... the other jumper, which provides power to the crossover rails, still shorts out a rail on each of the outside lanes (at the exit end fo the LC). Seems like the "Analogue" solution is to either:
1) remove the LC straights
2) install a switch to isolate the lanes

My findings seem to contradict post#10 of this thread (Johnny Mac)

Ummh... Am I missing something?
HookEm
 
#13 · (Edited by Moderator)
Well spotted HookEm


I posted the picture before I got my track, and should have checked.

It actually only leaves the Right, Positive rails joined. So dependant on how the analogue Powerbase is configured it may or may not work.

If positive is the common connection then it will be fine. Also if the Blue Dual Powerbase is used it will be fine.



New Instructions for continuity round the track.

On the Short Curled Top wire just cut just the Grey and on the Long Straight Bottom wire just cut the Black.
It must be done in this way, otherwise if two or more lane Changers are fitted there will be dead track between them.

Instructions apply to both RH & LH changers. You are effectively removing the connections to the outside rails, which go straight through.

What I don't understand, and this is the second one I have heard of. Is why the lane Change gets toasted, when the links are left in? You would only be able to control one car but the toasting does not make sense. The Digital signal on the rails is virtually DC anyway.

Rich
 
#14 ·
QUOTE (RichG @ 28 Dec 2006, 03:12) <{POST_SNAPBACK}>...
It actually only leaves the Right, Positive rails joined. So dependant on how the analogue Powerbase is configured it may or may not work. If positive is the common connection then it will be fine. Also if the Blue Dual Powerbase is used it will be fine...

Actually, a RH-LC shorts out one of the rails on each lane, and a LH-LC shorts out the other. So, if you install both LC's, both lanes would be connected together! (and a dual powerbase can't help that).

In any event, these new instructions do in fact work fine - Thanks!
Hook'Em

P.S. Perhaps adding a switch to the Digital powerbase is the 'ticket' to leave it in the circuit - I just hate to do that to this new toy! (I already have a switch on a my dual analogue powerbase, to isolate the lanes for digital mode.)
 
#15 ·
QUOTE (HookEm @ 28 Dec 2006, 18:08) <{POST_SNAPBACK}>Actually, a RH-LC shorts out one of the rails on each lane, and a LH-LC shorts out the other. So, if you install both LC's, both lanes would be connected together! (and a dual powerbase can't help that).

Right again HookEm,
must be loosing my touch.
That what happens when you think about something, but don't check it out in practice.


The final proposal I did check though.
Thanks for confirming that it works.

I think switchable Powerbases is the way to go if you intend to swap frequently. Toys are only new for a while.


The missed opportunity for Ninco, and the other manufacturers was to have not given the Digital Powerbase an Analogue mode. Would have added slightly to the cost as two output stages would be needed, but could have eased the transition from Analogue to Digital.

Rich
 
#17 · (Edited by Moderator)
If you are a fast driver?

Why should you choose a low numbered car?


Or How fast can you go before you get missed by the lane change?

This is calculated, perhaps someone would like to check the maths? Perhaps someone else might like to try it in practice. Higher numbered cars are likely to have more problem than low.

This is a link to the signal Ident thread.

QUOTE (RichG @ 27 Dec 2006, 11:48) <{POST_SNAPBACK}>The two halves of the square wave identify the car number and weather it is requesting a lane change or not, so similar to SSD.

The Low part of the square wave identifies Lane Change or Not. It is 0.5mS for no Lane Change and 1mS for Lane Change. This means that the Lane Changers only need to look at the Low Part of the pulse to work out if a car wants to change lanes.

The High part of the pulse identifies the Car Number. If you take the period in mS & multiply by 2 you get the car number. This means that the Start Line and Pit Stop only need to look at the High Part of the pulse to work out the Car Number.

So car 1 is 0.5mS and car 8 is 4mS.

So from this we know that a worst case ident signal, is car 8 changing lanes.

That gives us 1mS + 8mS. To be safe you would want two pulses so a total of 18mS.
Dead Strip is 4,5cm Long, in practice the usable length due to braid shorting is less than this, lets be generous to them and call it 4cm.

So how fast can you go over a 4cm dead Strip and detect a pulse train that is 18ms long?

Well I make it 222cm / Second or about 5MPH.

So does not sound like a lot to me. Even if they only wait for 1 pulse, which would be very risky, that is only 10MPH.
So have I got the maths wrong, or are high numbered cars going to struggle to change lane at higher speeds?
As a matter of interest the equivalent numbers for car 1 are 30 & 60 MPH.

Rich
 
#19 · (Edited by Moderator)
You might see this as a safety precaution then. If the car goes too fast it doesn't change lanes. Good thinking, or not at all?
2 m/s is only some 6.2 km/h that is really slow I think.

Sofar I remember only remarks of cars not missing lanechanges, but might this be because there were never eight cars on the track? No point in giving your car ident8 if you are with two or three drivers.

Rich, did you compute the max speed for SSD as well?

Greetings,

Don Quislot
 
#21 · (Edited by Moderator)
Was hoping nobody would ask that.
Even greater risk of getting the numbers wrong, but here we go,

Lowest LED frequency 2.4KHz for car 6
Convert to ms = 0.4ms *2 for two cycles = 0.8ms Looking good.

However effective dead strip (detection range of LED) only 1cm.


So that gives 1200 cm /second which is approx 25MPH or 50MPH if only 1 pulse.

So the LED part of SSD car detection looks fine, but we knew that.


Rich
 
#22 ·
QUOTE (RichG @ 2 Jan 2007, 21:15) <{POST_SNAPBACK}>That gives us 1mS + 8mS. To be safe you would want two pulses so a total of 18mS.
Dead Strip is 4,5cm Long, in practice the usable length due to braid shorting is less than this, lets be generous to them and call it 4cm.

So how fast can you go over a 4cm dead Strip and detect a pulse train that is 18ms long?

Well I make it 222cm / Second or about 5MPH.

Rich,

Extremely interesting and the principle is clearly right

Now I made the same exercise and came up with slightly different numbers. Let me explain


1- I took 1ms + 4ms = 5ms and honnestly could not understand your 1ms+8ms. Did I miss anything

2- I believe that the low pulse will be easily captured within 6ms because it is probably oversampled
with a nice algorithm.

This gives me 4cm/6ms = 6.67 m/s
. Three time your numbers and fast enough to deslot, I assume


What do you think ?

MatraMan
 
#24 · (Edited by Moderator)
Good job you are here MatraMan. Fortunately I have enough experience to know that I make mistakes with this sort of calculation


So yes my brain saw car 8 instead of the 4ms, and once you have seen it once, thats it you see it every time you look.
So agreed on the 5ms.

Agreed on the 6ms except that there is risk that you have captured a nice noise pulse because you did not wait for two full 1ms pulses which require a worst case minimum of 10ms.

What do you think?

Heaven knows what mistake I have made in the SDD calc


Rich
 
#25 · (Edited by Moderator)
QUOTE (Don Quislot @ 2 Jan 2007, 23:26) <{POST_SNAPBACK}>So, the dead strip for a Pro-x style changer for Ninco should be say 20 cm


Whatever the result of our two scientists' calculations
, the fact remains that you'll never be able to change lane at the top speeds I mentioned above on any type of LC (not even mine...)

If you take another look at the excellent Chesnay video, you'll see that LCs are placed on intermediate straights

Beppe
 
#26 ·
Just curious on how gate is triggered and closed.
Example, once gate is opened, does it close automatically, or is it timed? or does the next car hitting the deadstrip reset it?
If its held open, with the return spring in tension, is the solenoid powered during this time to hold it open?Also when car passes over deadstrip is digital signal still passing to cars chip?
Cheers
 
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