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Hi,

I have been testing my new APB and am current trying out the analogue.

I am using it with SSDC and Pit Pro.

I use SSDC to change from digital to analogue.

1) I have noticed that my digital cars seem so much less powered the the analogue ones.

2) When I rev the analogue cars with their rears wheels off the ground you notice a pulsing of power. This really affects the driveability of some of the analogue cars as some seem more affected by it. Some even pulse their way round the track.

Has anybody else noticed this and can it be fixed?

Cheers
 

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Greg Gaub
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Welcome to the club. Some people seem to have cars/bases that this problem is really bad on (See Chris99's post about his NSR cars pulsing), and some don't. It seems to depend on the cars(motors) and the base itself, as there appear to be many people that are unaffected by this... or they don't use analog mode enough to notice it?

As for the digital cars being slower, well... they are. The chips suck about 1.5v from the power in the conversion process. The exact same car (DPR, for example) will go noticeably faster with the chip removed in analog mode than with the chip installed.

AFAIK, the pulsing cannot be fixed. We're not even completely sure why it happens.

The voltage drop can be "fixed" but not easily. Fixing it requires replacing surface mounted parts on the chip itself. Specifically, the diodes (I think). RichG pioneered these mods, which have been performed by others such as MIH, GregK, gmyers, and more. That kind of work is out of my league, though.
 

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QUOTE (MrFlippant @ 31 Mar 2012, 19:17) <{POST_SNAPBACK}>AFAIK, the pulsing cannot be fixed. We're not even completely sure why it happens.
3 weeks since I sent an email to Hornby asking for help on this problem with no response yet. They say allow 30 days but I'm not optimistic as it's out of guarantee and I'm not in the UK, so we'll see.
Ironically the pulsing isn't as bad now although I haven't changed anything. In fact it has almost disappeared at the top end and my NSRs & other 24000+rpm (@15v) cars have actually become (just about) driveable at low speeds. I very much doubt it, but I wonder if the recent cold snap had anything to do with it as the temp didn't go above zero for a couple of weeks and the room temperature where I have my track was around 3 degs?

Stevef1964, try putting another car on the same track at the same time & see if the pulsing disappears? If it does then I am not alone, but I suspect this is a peculiarity of my powerbase.

Cheers
Chris
 

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I was involved in model railroading when Digital Command Control (DCC) first came out. For most inexpensive locomotives these DCC systems worked fine but for the more expensive loco's, with better quality motors, they tended to exhibit a similar problem, in some cases the engine would pulse but more common was a buzzing noise coming from the motor. The problem was that there was a constant voltage being applied to the rails. To get a DC motor to act like a variable voltage the signal was chopped into pulses of power so in effect the motor sees full voltage for a short period and no power. The faster you go the bigger the pulse width. The expensive motor were of such a quality that they would exhibit the pulsing or buzzing as the motor are being turned on and off at a high frequency, whereas the cheaper motors could not react fast enough to show the pulsing. The fact that Hornby are heavily involved in model railroading leads me to believe that they used a similar system for their Scalextric Digital System and we are experiencing similar problem to the early DCC systems. If this is the problem then I am afraid there is not much we can do about it!
 

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OK, I just made up a quick mod to prove something. I had postulated as Hornby had added more and more inductors just before release to reduce noise/EMI that they were causing a resonance in the circuit. I just made a test with a NSR Mosler fitted with an aftermarket Scaleauto 38000 outlaw motor that seems highly sensitive to the pulsing effect, test before with standard hardware, test after with all inductors removed. Result? No difference. So I was wrong. It is all in the motor reacting to the chopped pulse of the equivalent voltage PWM (pulse width modulated) waveform, so we can't do a lot about it in hardware. Adding a capacitor to smooth the waveform would screw up the digital. Andy is out on hols for a bit, I'll talk to him about maybe changing the chopping frequency, but the likelyhood is it would solve the problem for some motors and make it worse for others...
 

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Greg Gaub
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Maybe find out what frequency Slot.it uses for it's PWM. Though, maybe it's DC PWM? All I know is that their analog controllers can run any car with no pulsing.
 

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Thanks for the tests Riko.

All I can add is that, at the low end, my 2 Slot it cars have always been perfectly smooth but my 2 NSRs are not - both brands 21.5k rpm @12v I think (= 27k @15v??). Scalextric 25k @15v is in between, i.e. a little pulsing at min revs, but driveable. And to repeat the base info that I have never had any low end pulsing with cars under 21k @15v including Nincos & Scaley 20k.

As I mentioned above, at max revs, holding the back end up, the pulsing has all but disappeared (become unnoticeable) on all cars - certainly nothing like it used to be. But then again this was not a problem for normal running. And all cars run smoothly on an old analogue PB.
 

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QUOTE (RikoRocket @ 31 Mar 2012, 23:29) <{POST_SNAPBACK}>OK, I just made up a quick mod to prove something. I had postulated as Hornby had added more and more inductors just before release to reduce noise/EMI that they were causing a resonance in the circuit. I just made a test with a NSR Mosler fitted with an aftermarket Scaleauto 38000 outlaw motor that seems highly sensitive to the pulsing effect, test before with standard hardware, test after with all inductors removed. Result? No difference. So I was wrong. It is all in the motor reacting to the chopped pulse of the equivalent voltage PWM (pulse width modulated) waveform, so we can't do a lot about it in hardware. Adding a capacitor to smooth the waveform would screw up the digital. Andy is out on hols for a bit, I'll talk to him about maybe changing the chopping frequency, but the likelyhood is it would solve the problem for some motors and make it worse for others...
QUOTE (chris99 @ 1 Apr 2012, 08:12) <{POST_SNAPBACK}>Thanks for the tests Riko.

All I can add is that, at the low end, my 2 Slot it cars have always been perfectly smooth but my 2 NSRs are not - both brands 21.5k rpm @12v I think (= 27k @15v??). Scalextric 25k @15v is in between, i.e. a little pulsing at min revs, but driveable. And to repeat the base info that I have never had any low end pulsing with cars under 21k @15v including Nincos & Scaley 20k.

As I mentioned above, at max revs, holding the back end up, the pulsing has all but disappeared (become unnoticeable) on all cars - certainly nothing like it used to be. But then again this was not a problem for normal running. And all cars run smoothly on an old analogue PB.
QUOTE (MrFlippant @ 16 Jan 2012, 01:48) <{POST_SNAPBACK}>My iron decided to heat up today, so I tried both the ferrite man AND a bridge rectifier (from a drift car), and neither had any noticeable effect on the pulsing.

So what is the solution? I have no idea. Putting a lesser motor in the car would remove half the niceness of the car's performance. Getting a replacement APB is no guarantee that the problem will be less, and it could be worse. You could chip the car, but I guess it's possible that some chips will have the same frequency? You could go pure analog for analog cars, but that's a major hassle. You could go to a C7030 with Simple-H, but then you'd lose a lot of nice features you might already be enjoying.

I hope someone can help us on this.
--------------------

QUOTE (RichG @ 10 May 2012, 00:20) <{POST_SNAPBACK}>The need for the supressor is not an exact science. With some motors & chips they will run fine without either fitted. In general the higher the motor RPM the greater the need, also for some chips such as the SSD F1 they are virtually always needed.

The ferrite bead & capacitor work in combination as a low pass filter. The capacitor offering a low impedance path to the interference (hence why it is connected across the motor) and the ferrite bead a high impedance path (hence why it is connected in series).

The capacitor is probably the most valuable of the two, if this is working for you then things will probably be fine as is, however I would always recommend fitting them as a pair, particularily

Rich
Bit confusing as I'm quoting from 3 threads, but I took the liberty of quoting your new post Rich (Oxigen forum) just to see if there are any straws there.

Mr F's tests were more related to the high rev pulsing, but I notice most of my high RPM cars, NSR, Slot it, Ninco, don't have capacacitors/ferrite beads. I run them all in analogue mode on the APB so is there any benefit to adding them to a non-chipped car?

I ask because the pulsing at low revs has got really bad again and is now affecting one of the Slot it & one of the Ninco cars for the first time - Grrr!
Two months now & Hornby still haven't replied, even to tell me it's an inherent problem or that the APB wasn't designed with 21k+ motors in analogue in mind.

Cheers
Chris
 

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I dont think there is a straw there? The ferrite & capacitior on the motor are to prevent unwanted motor generated noise getting to the in car electronics. So as we are talking analog cars, without an in car chip I do not think it will offer any help.

Slightly perversely however the only way I can get this pulsing problem is with an NSR with a digital chip fitted running in analog mode.
I cannot get the problem with any of my pure analog NSR cars.

I think the clue to this problem is that it can be fixed by putting a second car on the track, even as I remeber another car which itself pulses? This indicates that there is some sort of resonance condition being setup, and putting the other car on the track then removes / damps that resonance. The resonance is presumably a function of motor speed & PWM frequency?

Further random thoughts:-

I do not think we have this problem with PB-Pro in analog mode?

I do not know off the top of my head what the PWM frequency for PB-Pro & C7042 are?

Does the problem exist whatever the track length /all the way round the track. Can it be seen with a car wheels in the air on just a Powerbase?

Is it possible to damp this condition with some components fitted either in the car or on the rails?

Rich
 

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QUOTE (RichG @ 10 May 2012, 09:01) <{POST_SNAPBACK}>Does the problem exist whatever the track length /all the way round the track. Can it be seen with a car wheels in the air on just a Powerbase?
Rich
Yes, it's consistently everywhere & every track and also on the PB track on it's own. I'm assuming you mean on the track attached to the PB and not connected to the PB internally.
,
,

QUOTE (RichG @ 10 May 2012, 09:01) <{POST_SNAPBACK}>The resonance is presumably a function of motor speed & PWM frequency?
The pulsing is in direct proportion to the revs. (I don't know what PWM frequency is).

QUOTE (RichG @ 10 May 2012, 09:01) <{POST_SNAPBACK}>I think the clue to this problem is that it can be fixed by putting a second car on the track, even as I remember another car which itself pulses?
I think this was true but it is is no longer the case - the second car now has to be a non-pulsing car one.

No-one else seems to have this condition at low revs so presumably it's an APB component that is misbehaving/out of tolerance?

Chris
 

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QUOTE (RichG @ 10 May 2012, 07:01) <{POST_SNAPBACK}>I do not think we have this problem with PB-Pro in analog mode?

No we dont.

On C7042 the problem exists with my NSR mosler with a large can King motor. No chip. No suppressor. With inductors all by-passed.

Not many componnts left in the circuit Chris, but something is playing up. It might be the drive chip, but it doesn't make a lot of sense.
 

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Mark Wain
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I recently figured out analogue through SSDC (cheers to all who helped!)


I too can have a power pulsing problem sometimes? if i turn back to digital through SSDC then back to analogue it will work fine for a minute or so then play up again.

Weird thing is it will not do it everytime some days its fine?
 

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Mark Wain
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Could be, could be humidity too I guess, not a big problem for me, just a minor irritation lol Just nice to take the "shelf queens" out for a few laps every now and then
 

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OK, some progress. Possible botch solution found for low rev pulsing - using a capacitor .... how best to implement it?

If I put just the capacitor ref 104M (without the ferrite bead) from an old SCX motor across the rails, it has the same effect as when I put another car on the track at the same time, ie the low rev pulsing disappears (now it's only cars with capacitors that work this magic - a few months ago all cars seemed to work!?)

Anyway, as I don't have any electrical theory knowledge I need expert advice - should I just solder the capacitor across the rails under the powerbase track - one for each track. Alternatively, is there somewhere inside the PB that I could just solder it one single capacitor on the power output to both rails in analogue mode?

More importantly, in principle, is this an harmless inert solution and safe? Or could it burn out or screw up anything else like digital mode or lap-counting?

Cheers
Chris
 

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Greg Gaub
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If that works, then shouldn't it also work across the braid ends of the lead wires? For that matter, why wouldn't the same work at the motor end, since it's all in parallel whether it's on the rail, braids, or motor... right? I'm asking, 'cus I don't know.
 

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If you take the bottom off the Powerbase there should already be a capacitor (103) across each of the tracks? Are they there?

Worth just trying a couple of experiments first.


Does to 104 cap (10 x the size of a 103) work anywhere on the track?

Can you try putting it across the braids of the car & see if that works?

Does a 103 cap work or does it need the 104?

There is a limit to the size of cap you use. It supresses interference, however at some point it degrades the digital signal.

You mention low rev pulsing, have you got pulsing at other revs?

In terms of where you put it, I would solder it across the rails of any convenient track piece in case it needs to come off again.


Rich
 

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Thanks for the quick replies.

QUOTE (MrFlippant @ 10 May 2012, 18:35) <{POST_SNAPBACK}>If that works, then shouldn't it also work across the braid ends of the lead wires? For that matter, why wouldn't the same work at the motor end, since it's all in parallel whether it's on the rail, braids, or motor... right? I'm asking, 'cus I don't know.
MrF, Yes it works, so the other solution is to put caps in all cars.

QUOTE (RichG @ 10 May 2012, 18:43) <{POST_SNAPBACK}>If you take the bottom off the Powerbase there should already be a capacitor (103) across each of the tracks? Are they there?

Worth just trying a couple of experiments first.


Rich
I took the top off a while ago & took this pic:

Is it the brown components that you are talking about as I can't see 103 on them?


QUOTE Does to 104 cap (10 x the size of a 103) work anywhere on the track?Yes, no difference.

QUOTE Can you try putting it across the braids of the car & see if that works? Yep works the same.

QUOTE Does a 103 cap work or does it need the 104? No, not now. I haven't got any loose ones but if I put a car on the track with 104M (like a Scaley F1) it completely removes the low rev pulsing. The cars with 103M (like a Scaley Skyline) don't eradicate it completely but I think they used to? (but that might have been because they increased the rpm with two cars on the track & smoothed out the motors).

QUOTE You mention low rev pulsing, have you got pulsing at other revs? Yes, it is in direct proportion to the rpm but becomes unnoticeable between around 50% and maybe 90%, and then at full speed there is a more regular pulsing which you don't notice unless you hold the wheels off the track but this pulsing is normal for APBs I think.

At min revs the car actually does stop start hopping a couple of times a second - power then nothing - worse than in the video above. Putting the 104M capacitor on smooths it out and increases the rpm but it's still smooth right down to min revs with wheels off the track.

QUOTE In terms of where you put it, I would solder it across the rails of any convenient track piece in case it needs to come off again.
I can attach it to some spare power tap wires whilst testing.

Cheers
Chris
 
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