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Conditionally Human

Comparing Digital To Analogue

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I Just finished reading Dave Changs new book "Digital Racing in 1/32 Scale".

 

On pages 84 and 85 is a comparison table of eight different digital systems (I didn't even know that there where so many).

 

Third last entry on page 84 is "Speed steps". As far as I can see, this the main difference in car control between analogue (unlimited speed steps) and digital (limited steps, controlled by pulse width modulation).

 

The chart says;

 

Scalextric SSD = 64 (but I think the in car chips only recognizes 32).

SCX = 13

Carrera, Davic and Slotfire = 16.

Ninco NDigital = 16 (but standard controllers only recognize 11 and progressive controllers only 14).

Scorpius and O2 = 256.

 

It's hard to explain, but when I drive in analogue, I eventually get a feel for the car and the track.

 

It may be a combination of factors. The tires warm up, so does the motor, so do I, and for a while, I'm "in the zone" and control feels instinctive (it's at this time that the car can do some amazing stuff). With my current set up (Ndigital and Slot-it controllers which gives me the full 16 speed steps available) it's not the same.

 

I'd like to hear from anyone lucky enough to have tried O2 or Scorpius for there thoughts on this.

 

I have other questions, but this is the first.

 

Price will NOT dictate which direction I head in. I've spent enough now that it just has to work right.

 

If it doesn't "I'll be very angry. Very angry indeed"

 

Peter.


"At last, after two thousand years of work, the illudium PU-36 Explosive Space Modulator" - Marvin the Martian

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I have no desire to go to digital unless I can do it on a routed track without magnets.

 

I also like only having two wires in the car and not having to worry about 'frying a chip'. Some people seem to fry more chips than a fish and chip shop.


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You can certainly run digital on a routed track, and there's no need to put magnets in unless you really want to. In fact, magnets can be removed from all cars right now. You will find many people have created routed tracks and run digital - the hard bit is the lane changing and lap counting (since all cars can be in one slot) Slot forum has a number of threads discussing this option.

 

Chip frying relates more to the 'toy' market chips being over powered by enthusiasts who a) increase track voltage beyond design, b: replace the motor with something beyond design c) add excessive magnets to maintain 'drivability' d) do a subtle combination of all. But, surprisingly, they fail to also uprate their chip to cope with their other enhancements. Reality is that chips are very robust when they are kept within design limits.

 

In regard to throttle steps, it appears the decision to stick with a few steps is likely forged from those who run TruSpeed controllers on analog, and they only have a few individual steps - maybe even to those drivers who have zero ohm throttles! However, there are many who argue that any more than 32 steps means that individual steps cannot actually be detected by the driver. So going as far as 256 steps may actually provide little more than technical argument. (Its a bit like CDs - if they used more bits to encode your music, would you really hear the difference?)

 

Ian

Edited by MIH

Linux: A '90s reincarnation of a '80s Operating System based on a '70s design philosophy

Website: www.electricimages.co.nz

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"Its a bit like CDs - if they used more bits to encode your music, would you really hear the difference?"

 

A bit off topic, but I am a HiFi enthusiast also and can certainly hear the difference.

 

For serious music listeners the CD format was far too "low rated" . Initially it just did'nt sound natural (in fact quite harsh), partly because of low bit rates and high frequency cutoff which took out all the high harmonics of instruments.

 

Yes I know most people can't hear above 16khz, but almost anyone can hear the difference when these harmonics are removed, newer CD players tried to create these missing frequencies, but newer "hard disc" methods with much higher bit rates, SACD, DVD-A better. Good turntables (not the toy/plastic ones with piddly mechanics ,wobbly tonearms ,poor bearings, cheap cartridges and isolation methods which most people had) can reproduce up to 100kz.

 

There has been an increase in vinyl sales continuously for the last 10 -20 years and now there are hundreds of good turntables available, even a number of recording artists are returning to analogue recording for better sound quality and recording/mixing albums for vinyl release( Mark Knopfler, Ben Folds, Neil Young etc).

 

Records renewed popularity is similar to a feeling I get that there currently is a "slotcar mini revival" around the world after everyone went radio control and other pursuits way back after slot cars demise.

 

 

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Given that a Scalextric analogue controller has 52-53 turns of wire. Even if the wiper can pick up each individual wire that is only 52 steps. Add to that some cars don't start to move until the wiper is at say 40% some times more. I'd say 32 steps or less is what most people drive with so Scalextric may have done their homework and go it right. Parma the defacto std. has about the same number of turns but I cannot access to count without dismantling.

 

So your lack of "feel" may have nothing to do with the number of speed steps.


Outside the box looking in.

------------------------------------

You don't own stuff: Stuff owns you!

------------------------------------

Having a cold drink on hot day with a few friends is nice, but having a hot friend on a cold night after a few drinks - PRICELESS.

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Thanks Guys.

 

Willie, I'm a Hi-Fi enthusiast too and I understand what you're saying in relation to vinyl. It's also been argued that valve amplifiers sound warmer than digital. I think the analogy here is a good one. Logic would suggest that a digital signal should be able to carry much more detail with less unwanted background noise. In other words, digital should be better, but not everyone agrees.

 

Regarding the steps. I started with standard Ninco digital controllers (11 steps) and upgraded to Slot-it (15 steps) and noticed a huge difference. I can only dream of 32 steps.

 

Another part of the problem I think is dead strips. The double lane change curve has four, each measuring 43mm in length. Add four plastic flippers and that makes each dead strip on the curve 157mm. All things add up to it being very hard to drive through this corner under control.

 

Scalextric have metal flippers that sometimes carry a current and Scorpius has live flippers.

 

I don't hear any Scalextric Digital users being as frustrated with lack of feel as I am, but am I asking too much from digital?

 

Thanks.

Edited by Conditionally Human

"At last, after two thousand years of work, the illudium PU-36 Explosive Space Modulator" - Marvin the Martian

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"Its a bit like CDs - if they used more bits to encode your music, would you really hear the difference?"

 

A bit off topic, but I am a HiFi enthusiast also and can certainly hear the difference.

 

For serious music listeners the CD format was far too "low rated" . Initially it just did'nt sound natural (in fact quite harsh), partly because of low bit rates and high frequency cutoff which took out all the high harmonics of instruments.

 

Unfortnately a misinterpretation of what I said, and not quite the link to 'number of steps'... I'm not talking about how many samples per second, but in fact whether you have 16 or 17 bits in the original sample. While the data size of sound most certainly has an impact, the different types referenced focus on the sample speed - usually considerably better than CD. This scenario more closely matches the packet update interval in digital slotting.

 

The packet update rate (ie how often you tell the cars it proper speed) actually has more impact on drivability than the granularity of the motor speed. To get maximum lap times, then you need to perform speed and brake commands as closely as possible to the best track location. This is very possible in analog, and is solely driver skill. However if the updates only go out, say 10 times a second, then your car may have travelled over 100mm (when at speed) before its next command arrives.

 

The thing about digital racing is rethinking what you need to do. No longer is it just pure speed. Its now about timing your attack to overtake traffic at the right time, planning proper braking, and finding the best racing line.

 

Digital racing becomes more about getting one over the opposition, which can actually include blocking and (for my son anyway) flipping you off the track with a wee nudge from behind on the corner.

 

ian


Linux: A '90s reincarnation of a '80s Operating System based on a '70s design philosophy

Website: www.electricimages.co.nz

InCar-PRO: Chip Main Page

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However if the updates only go out, say 10 times a second, then your car may have travelled over 100mm (when at speed) before its next command arrives.

 

Something I had not considered. I thought it was instantaneous! So that info is more important than the steps of the controller.


Outside the box looking in.

------------------------------------

You don't own stuff: Stuff owns you!

------------------------------------

Having a cold drink on hot day with a few friends is nice, but having a hot friend on a cold night after a few drinks - PRICELESS.

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I thought it was instantaneous!

It'll never be instantaneous - but it can be imperceptable. No matter what happens, the analog of the throttle has to be converted into a digital speed value, that value has to be encoded into a (or the next) packet, sent somehow to the car as a data stream, then decoded, validated and converted back into car motor speed values. It can be real fast, but its never instant.

 

The scaley system sends packets at variable speed because the packet size changes based on the data. From memory, it sends between 50 and 90 packets per second.

 

Ian


Linux: A '90s reincarnation of a '80s Operating System based on a '70s design philosophy

Website: www.electricimages.co.nz

InCar-PRO: Chip Main Page

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A few thoughts are going through my head right now (that's good for me at my age);

 

1. Dead strips.

 

Maybe I'm placing too much of the blame on them. If "A standard (1/32 scale) slot car traveling at speed can cover 6 meters in one second", then the dead strip is less of an issue than I thought it was.

 

2. Throttle control.

 

Speed Steps are one entry in Dave Changs chart. Other entries include "PWM (pulse width modulation) frequency" and "Frequency of Car Speed Messages". I assume they both have an effect.

 

I think I understand PWM. In analogue, to achieve 1/3 speed, 1/3 power is applied all the time. With PWM, full power is applied one third of the time (signals are then decoded by the in car chip and power delivered to the motor). Nincos PWM frequency seems low at only 120Hz where as Scaley have 300Hz and O2 and Scorpius have 4.5KHz & 4KHz respectively.

 

The frequency of car speed messages I am less clear on. But, I have the book and I'm determined to keep reading till I understand it.

 

Thanks again, Peter

Edited by Conditionally Human

"At last, after two thousand years of work, the illudium PU-36 Explosive Space Modulator" - Marvin the Martian

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PWM speed is really more important to the motor technology than the perceived performance to the driver. If the PWM sample rate matches the packet rate accurately, then having a faster PWM rate won't have an affect on the speed responsiveness to the driver. However, if the PWM rate is 'better matched' to the motor, then the efficiency of the motor could increase, and could provide better torque. This would assist in acceleration, especially from standing start (assuming less then 100% power). But this would not necessarily have any improvement on the positional responsiveness on exactly when a braking or acceleration command gets actioned on the car itself.

 

Ian


Linux: A '90s reincarnation of a '80s Operating System based on a '70s design philosophy

Website: www.electricimages.co.nz

InCar-PRO: Chip Main Page

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On the subject of "Frequency of Car Speed Messages". (This goes to show that I'm getting older (and so is my brain)).

 

Study as I might, It's all just a bunch of numbers to me.

 

But... if the numbers are to be taken literally, then Ninco's frequency of car speed messages of 20-70Hz reads well. This then, is also not the problem.

 

Acceleration Curve perhaps? I've only ever used my Slot-it controllers in "LIN" mode. I've been too lazy too look up spread sheets on setting different curves for that particular mode (though I know the controller supports it).

 

A combination of factors? Or... am I missing something entirely?

 

Peter.

 

P.S. I'm going wireless whatever happens, so, thanks for every ones input.

Edited by Conditionally Human

"At last, after two thousand years of work, the illudium PU-36 Explosive Space Modulator" - Marvin the Martian

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Faster lap times, better control and better brakes with your Scorpius controller or your money immediately and cheerfully refunded :)

It can also run with the new 7042 SSD PB and run on analogue once our analogue plug in module is released.

 

 

Rick


The best form of satisfaction is success.

www.scorpiuswireless.com

 

 

 

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Thanks Rick.

 

Everything I've read on the subject suggests that, in terms of functionality, Scorpius has no peers. That said, I'm still undecided between O2 and Scorpius.

 

The most desirable advantage of Scorpius over O2 for me is the LCD display on the controllers (my biggest issue with digital so far has been control). Then, there are other things such as PEARL (Programmable Electronic Assisted Racing Line), programmable ghost cars, extra pit-lane features and live flippers.

 

In O2's favour is slightly lower cost, and the fact that I can implement the system changeover to my Ninco track in small stages.

 

Warning!! For anyone sick to death of me going on about dead strips, I advise you to stop reading now.

 

Without wanting to put too finer a point on it, I HATE dead strips.

 

In the case of DAVIC systems (which also use dead strips for car detection), I expect that it works quite well because of the large, fast, multi-lane club tracks that it is usually found on. On tighter home circuits though, they are less than desirable. Live flippers sound like the answer but if I go with O2 on my Ninco track, it won't be an easy upgrade. Ninco L/C's use plastic flippers which would need to be swapped for metal ones. Then, the flipper has to be electrically insulated from the rails (Ninco track features a plastic inner sleeve in the slots, so maybe this part has been done for me), and then the installation of a latching relays.

 

I saw a thread on this forum polling members if they preferred racing or tuning. Easy answer for me. It's all about racing. I expected digital to more involved than analogue but here I am, two years on and over $5000.00 poorer and still decidedly unhappy. And, don't want to solder at all if I can help it. I just want to race.

 

But.... I won't be going back to analogue. It's digital wireless or it's nothing (life wasn't meant to be easy).

 

 

Peter.


"At last, after two thousand years of work, the illudium PU-36 Explosive Space Modulator" - Marvin the Martian

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Cool. The changeover to Scorpius from Ninco however will be the same procedure as any system. Not sure if you can make it down one day but youre welcome to see the system anytime.

 

Rick


The best form of satisfaction is success.

www.scorpiuswireless.com

 

 

 

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Buy Australian! Scorpius is best. Rick came up with the idea and then the world copies him....


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.............................PM me for C7042 Aux to PC cables............or Pit-Pro...

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I race both analog with a club, and digital with a club (SSD). While i won't claim to be the best and most "tuned in" racer of all time, I ain't bad. I feel no difference between the control of my cars that cannot be attributed to the controller itself. When I use my slot.it controller for my SSD, it's the same, with the only exception being that I don't have adjustable brakes. With SSD they're either on or off, unless you upgrade the chip and use computer control of the power base (which I don't yet have). That, and the chip electronics drop about a volt off the top end. Usually I'm turning power down since I run primarily magless, so that's not a problem. I don't notice ANY difference in responsiveness on acceleration, corner control, and other important facets of slot car racing. With the aforementioned chip upgrades, both software and hardware, SSD cars can run any 1/32 scale motor (and many 1/24 ones), and have adjustable brakes, working brake lights, and fully adjustable throttle curves.

 

Scorpius and oXigen are both great systems, but they aren't the only way to get great digital slot car performance.

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Only thanks to Rich, Riko, Andy and Ian. great work by every one except Hornby :)

Sorry couldnt help myself :)

Ok hat, coat........

 

 

Seriously digital is getting better and better, can you imagine in ten years time?

 

Were currently working on Wi-Tricity and mind control, then thats it, Ill be able to concentrate on tuning and racing more.

Edited by aussieslotter

The best form of satisfaction is success.

www.scorpiuswireless.com

 

 

 

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