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Discussion Starter · #1 ·
Much of the pre-digital release discussions of how digital works was grounded in DCC theory, and it looks like this is the way scalextric have gone (pulses of + and - 18volts or there abouts, the widths/sequence of pulses used to send packets of data). This symmetrical system means amongst other things that the car will run in either direction on the rails.

This has been described as 'an AC grid' elsewhere, and although it is not AC (which involves a regular sin wave), the reason for the term is clear.

Carrera on the other hand has been described as a 'DC grid', and the cars will not run in either direction. How does this encode its data then? is it DC with a carrier signal on top? does it vary between +18 and +0? or some other way?

Cheers for any info or insight that anyone may have

Dave
 

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Voodoo.

It's the key to the whole slot racing thing.
 

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Beppe Giannini
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Hi Astro,

funny - I was thinking exactly about this (you know, great minds...)

Now, assuming that we are not in the 00 address situation discussed here :

http://www.slotforum.com/forums/index.php?...topic=3443&st=0

the fact that with Carrera you always have full DC voltage across the rails might indicate that their system isn't DCC but rather ACC - like the first version Davic, where signal is superimposed on power

Should that be the case, it wouldn't be too good....

Julius


Ciao

Beppe

P.S. : somebody jog Wankel - he seems to be stuck in voodoo mode
 

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Julius Wilkko
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Hi!

Agree with Wankel, there are so many unexplained things with these electronic gizmos they can be only explained with voodoo magic.


Beppe, I did the digital rite unintentionally as I got PRO-X track assembled. Placed McLaren and Ferrari on separate lanes. Drove couple of laps with Ferrari, then I changed the lane and smashed to back of McLaren that was standing still at its original position. You were right. This will be the digital initialization rite.

Well, I´ll get my oscilloscope and see what kind of signals can be found at PRO-X. May take some time.

Julius
 

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QUOTE (lordjw @ 17 Nov 2004, 15:57)then I changed the lane and smashed to back of McLaren that was standing still at its original position. You were right. This will be the digital initialization rite.
<{POST_SNAPBACK}>

Did something very similar at the Pendle scalextric digital demo. Hugs stopped her car to talk - left it on the trck. I was aware of this, but watching my car raced blissfully until smacked into the back of the other one


Really going to have to read the road and watch AHEAD of my car rather than staring AT my car

looking forwards to your oscilloscope findings, Lordjw!
 

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QUOTE (Xlot @ 17 Nov 2004, 16:22)Hi Astro,

funny - I was thinking exactly about this (you know, great minds...)

Now, assuming that we are not in the 00 address situation discussed here :

http://www.slotforum.com/forums/index.php?...topic=3443&st=0

the fact that with Carrera you always have full DC voltage across the rails might indicate that their system isn't DCC but rather ACC - like the first version Davic, where signal is superimposed on power

Should that be the case, it wouldn't be too good....

Julius


Ciao

Beppe

P.S. : somebody jog Wankel - he seems to be stuck in voodoo mode
<{POST_SNAPBACK}>

Why would that not be a good thing?

One good thing about the way carrera does things is that you can use a variable aftermarket power supply to increase voltage to the track.
 

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Discussion Starter · #8 ·
to be fair - whatever system Carrera have adopted, it seems to work (at least with new braids on new track!)
 

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Discussion Starter · #10 ·
my understanding with the scalextric is that you can provide more current, but not more voltage. (could be wrong though!). I don't know how carrera works at all.
 

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QUOTE (astro @ 17 Nov 2004, 22:07)my understanding with the scalextric is that you can provide more current, but not more voltage. (could be wrong though!). I don't know how carrera works at all.
<{POST_SNAPBACK}>

With carrera, you retain the abilty to increase the voltage such that the cars run faster (or decrease for slower although reports that below 12V does not work) Additional power supplies up to 10amps have been tried without frying the cars or LCs.
 

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I was relayed an email from Carrera Germany regarding the availabilty of braking in future Pro-X release. The system meets my expectations *except* that it does not provide brakes. Her was their reply. Babelfish tells me that braking is on their "plate". If they can get braking to work, I will be very satisfied with pro-x.

Das Problem mit der Bremse liegt auf der Platine und ist uns bekannt. Wir sitzen auch
gerade an der Lösung des Problems, kann dir aber derzeitig nicht sagen wann wir fertig
sein werden bzw. wann die Lösung verfügbar ist.

Er kann sich aber bei Problemen oder fehlenden Informationen zu PRO-X gerne an
unseren Distributeur in den USA wenden.

The problem with the brake is appropriate for us on the plate and is well-known. We sit also straight at the solution of the problem, can to you however presently not say when we will be finished and/or when the solution is available. It can turn however with problems or missing information to PRO x gladly to our Distributeur in the USA.
 

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Julius Wilkko
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Warmed up my oscilloscope and did fast evaluation of the Carrera PRO-X system. This is Carrera control unit that was under examination.



Opening of the backplate reveals single sided printed circuit board. Microcontroller seems to be running at 4MHz speed. I have to make a comparison here, Scalextric Sport Digital system has a controller which is running 40MHz, ten times faster.



Connections from PCB to track are made with very thin wire. Wires are connected to track with push-fit copper strips. Not very convincing contacts.



One single 2SJ325 transistor feeds power to all cars. Rated power dissipation of this device is 20W. Carrera power supply plus pole is connected directly to this control transistor. Transistor output is connected to plus-rail. Power supply is rated 14.8V. This gives us very rough estimate of maximum constant current I=P/U=20W/14.8V=1.35A. Each car can have 1.35/4=0.3375A.



Data and power is sent to car via plus rail. Datapacket contains two bytes. My guess is: one control byte and one data byte. Time between data packets is about 14.8ms. That means that data of each car is updated every 4x14.8=59.2ms. In practice this means that each car receives new data about 17times/sec. There is no data at minus rail. It is used purely as a ground. This explains why the data is updated with such low rate. Faster data rate=more cars would decrease the effective voltage of the plus-rail.





This system is very simple and clearly aimed for cheap-toy-market. Every component has been designed to be as cheap as humanly possible. Communication is very simplified and slow.

My apologies if I have offended someone with my comments. I have tried to be as objective as possible.

Julius
 

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Discussion Starter · #15 ·
Thanks for that thorough analysis! It is great to have some propper science to understand the different systems rather than heresay and voodoo!
 

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Beppe Giannini
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Very captivating reading, Julius (I only wish I understood more than 15% of it !!)

Is it totally stupid to say that Carrera's system is midway between ACC and DCC ?
If I interpret your oscilloscope displays correctly, you have a continuous DC voltage interspersed with digital messages

Anyway, you make it very clear that a larger number/more frequent messages would eat away power

Ciao

Beppe
 

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Okay, hands up who understood Lordjw's explanation.

Now, with Voodoo, you just stick pins in things and it works.

Here's the science bit - pin+thing=action.

Much easier.
 

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Real world testing with uprated 10amp variable power supply has shown an ability to increase voltage to near 20V. Cars are proportionally faster and 4 cars on circuit feel no power loss or interference from other cars. Perhaps this is operating outside parameters of components, but it works nonetheless.

Edit: OK, who am I kidding, it is junk!
 

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I can almost spell "oscilloscope," so hang in there gang, this ain't technical.

Having said that . . .

So ... hummm that means no after market 0 to 20 volts, 10-Amp power supplies for Pro X, right? What about our friends from Scalextric, as to beefing up available power and all?

Also means no running of "hot" amp sucking motors, .375Amp is not all that much. Especially if the available power is diluted as cars are added.

I do like ability to add torque & horsepower. Therefore, amps & voltage are always considerations.

Please expand on 4MHz versus 40MHz? Other than faster cycling, are their any other advantages to 40 versus 4?

You talked about toy like, based on your photos, even a lay person can see it is hardly robust. Do you know if Scalextric's version is any better than Carrera's?

Not keen on "one anything being totally responsible" ... yet poster says, "One single 2SJ325 transistor feeds power to all cars." Yet another hummm . . .

Seems the more I read of the two contending digital systems the more I wonder if all was thought out relative to standing up to abuse? As in very light weight material used ... based again on photos. As well as possible inability to readily, easily, and more or less economically enhance the system to serve present and future needs. Does cause one to pause.

The pause being, most commercial even most home systems do get abused. Appears the digital systems may be more prone to breakage and less prone to being able to be "fixed" without ordering requisite items to replace damaged circuit boards, transistors, chips, what have you.

Meaning one could screw up and end the game until such time as parts are ordered, replete with requisite "waiting," then replacing "fried" component or components. Moreover, the lay person "hoping" he/she ordered the right "stuff" for the fix.

Which makes many ... me ... prey to savvy sales people with good sales speak, talking one into ordering more fix it stuff "just in case." I can almost hear the sales person's take away close, "if you want to ensure future happy slotting, best you order these other board based components, just in case you missed a fried item or two." Almost makes me think of what's left at the bottom of a bucket of KFC.

Could mean some serious downtime between screw ups, let alone components mailed back and hoped for crediting of one's VISA, MsCd.

Sorry to sound bleak ... yet feel I'm close on some of it.

Cheers
 

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Julius Wilkko
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Beppe,
I would not compare it to DCC. I would compare it to serial RS232 communication where signal line powers the target device. You just send the data so infrequently that you don´t disturbe the power distribution.

Darainbow,
I would not say that it is junk, it is designed to be a toy. Propably for younger audience, as PRO-X packaging says: AGE 8+. Becouse it is a mass-produced product it has been designed to be as cheap as possible. You should be able to upgrade this system by changing the 2SJ325 transistor for more powerful model. Maximum allowed voltage across 2SJ325 is 30V, so you still have some room for experimentation.

old new slot guy,
You can experiment with more voltage. I would say 20V is still on the safe side, darainbow has apparently experimented near 20V.

I´m afraid that you will not get much torque/horsepower with any digital system.

4/40MHz? this tells me that Carrera unit does only simple tasks, no calculating performance.

All the power for the cars go through 2SJ325. Its performance determines available current for the cars.

I am sure this system performs very well as a toy. It is quite robust and rails have short circuit protection. You could think this system as a "my first digital" that grows future digital slotracer generations. Old pharts in the year 2046 can look back and recall the memories of the past when Carrera PRO-X was their first set. It was fun for awhile until it got trashed and thrown away. How they will then regret that they didn´t keep it.

Julius
 
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