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I just completed some testing with an aftermarket power supply on my 82' Pro-X layout. The supply is the LOKO DPS 400GL, 4-18VDC, 30Amp power supply. For purposes of the test, I used the 10Amp quick connect outputs.

For point of comparison, the Stock Power supply is rated at DC 17V Max (DC 14.8V, 1450mA)

Before describing the results of my test, I had just completed wiring four power taps into the layout in a "star" configuration. I take a direct feed from under the power terminal, and this is split and sent to four locations around the track. This is duplicated for each lane. (It is important to note that the track has only been locked together in 3pc. chunks and has not yet been bolted to the table. There are some visible cracks at some joints, so the connections are not yet ideal. There is a 25' stretch without any power taps where there is a mild loss in power. There is another 15' stretch where there is a slight loss in power. Car drives with less torque at these spots. ) By proceeding with the aftermarket power at this point, before adding more taps, I would have an additional datapoint to see how the aftermarket power copes with these spots.

Sacrificing one of my stock power supplies, I opened the connection plug with a star driver in an attempt to cleanly wire my project. Unfortunately, I have been using 14Gauge solid copper wire for all my power taps, and this would not fit within the connection plug. The wire used by the power supply is stranded copper, probably 18Gauge.

However, I was able to trace the positive output. The wire coded with white is hot and the other is ground.

So I took the quick and dirty approach which was to snip the plug and solder directly to the wire. This is sent to the 10Amp outputs of the Loko power.

Turned on the power and got the startup beep and light from the black box! Good so far. .. The power supply was in the center detent position and reading about 15V.

Took the car for a lap. Drives well. No problems. Feels *maybe* slightly weak compared to my memory. So I started to A/B between the stock supply and the aftermarket. By listening to the tone of the engine and test laps, I would say that 15.5 on the viewmeter is the approximate output of the stock supply. This is slightly above half the sweep of the variable control.

I lowered the voltage to see what happens, and there is a gradual drop in engine speed til around 11-12V where the black box signals an error with tone and light display (maybe a code that can be read by the knowing?) So 12V is the practical minimum to use the system in a detuned fashion with cars that will be probably 25% slower with less torque.

Taking the variable control in the other direction, I was pleasantly surprised. The upper half of the sweep provids a linear increase in engine speed up to a voltage of around 18.5V (full) on the viewmeter. While the meter only registers an additional 2V, the effects are more than subtle in the upper half of the sweep. At the higher voltage, the car has a higher top speed (by probably about two "full tones", maybe an additional 2K rpm???) and these heavy nascars drive with more gusto. I am sure a lightweight FLY car converted to Pro-X would SCREAM.

I would say that the feeling of driving at higher voltage is akin to using an analog control with less resistance, or taking the magnets out of a car. The course needs to be driven with more finesse and I find myself driving in the lower band of the throttle.

Also, the additional power helped moderately to overcome some of the "soft" spots in the track, although they will still require power taps.

Additionally I wanted to see how many amps a car would pull under full acceleration. With wheels lifted, very little. While driving about the track, at most I saw was less than .5. However, with wheels held against the track to still alow some rotation, the single car registered close to 1.5Amp draw! That is close to what the stock supply will provide. I note that the viewmeter is probably not very accurate so this is just a ballpark observation. However, the additional amperage of the aftermarket power supply will probably be necessary when running multiple cars. I will give that data in a later report.

Overall, I am very impressed with the way the Pro-X system responds to aftermarket power. It retains an old school "feel" in the way it responds to the additional power and so far, the black box, the cars, and the lane changers have not complained.

Edit: I just did some additiona A/B testing with the stock supply and while the engine rpms are about the same at 15V, the car definitely has more torque.
Maybe they provide a cheap supply knowing that the aftermarket will take care of the enthusiast?

Edit#2: Did some more testing. Cruising around the track, will see mostly .25Amp draw. Previsouly had said .5. So technically, the stock supply may work for four cars, but I suspect you would feel other cars.

 

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Fast Co.
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Very interesting tests darainbow. I'll be watching to see how the system responds with multiple cars.
Thanks

Steve
 

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Soren Winkler Rasmussen
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Thats very usefull information darainbow ... thank's a lot


Your measurements might indicate that it's possible to drive more cars on the track than I previously thought. Judging from your readings, it's perhaps not very likely that all cars on the track draw more than 1A simultaneously? ... except perhaps at race start, where the cars will typically be spaced evenly across the slots anyway.

Another feature of digital control, that we could use to our advantage, is the time driven modulation, where power delivered to the motor, is not depending on the voltage level of the supply.

By increasing the track voltage and lowering the pulse duty cycle accordingly, you can deliver the same amount of power to the motor even if the supply voltage is higher.

Example: instead of a 12V supply we use a 24V supply, and modulate the motor from 0 to 50% instead of 0 to 100%. This will give us the same power to the motor, at only half the current drawn from the slot. In other words V x A is the same, only V is double and A is half.

This way 5A per slot effectively translates to 10A per slot of an equivalent 12V system.
The MC33887 H-bridge motor controller is specified for full rating up to 28V and can even handle up to 40V at reduced specification, so this will not even require a hardware change.

Are there any draw backs with this solution
... I can't see any


...

Last but not least a word of caution. You increased the voltage to 18V on your track without problems, but please beware that the capacitors in you electronic circuits are rated accordingly (minimum 25V types) ... I saw plenty of 16V capacitors in the Scalextric Digital pictures, but maybe SCX uses higher rated capacitors?.

I don't want to sound pessimistic, and perhaps there's no problem, but I'd hate to see you fry your precious digital equipment, just because they might have cut their design specifications a little too close for comfort ... I sometimes wonder what length they will go to, just to save a few pennies


A problem like this wouldn't show it self immediately, but would stress your capacitors and effectively shorten the lifetime of your digital controls.

I think it's worth a quick check ... just to be on the safe side

You can normally read the voltage directly on the electrolytic capacitors.

Best regards
Søren
 

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Discussion Starter · #5 ·
Thats very usefull information darainbow ... thank's a lot

***
No problem at all.

By increasing the track voltage and lowering the pulse duty cycle accordingly, you can deliver the same amount of power to the motor even if the supply voltage is higher.
***
I suspect carrera might be doing something like this. In a preliminary test I did by putting an analog car on the rails, I suspected that the analog car was slightly faster. It may be that that particular car was slightly faster. In any event, it is not night and day. I suspect the way to determine if they are using this strategy is to measure voltage from outputs of chip and compare it to rails. Where is my multimeter?!!??


Last but not least a word of caution. You increased the voltage to 18V on your track without problems, but please beware that the capacitors in you electronic circuits are rated accordingly (minimum 25V types) ... I saw plenty of 16V capacitors in the Scalextric Digital pictures, but maybe SCX uses higher rated capacitors?.
***
I would need to open the box and check the components against their specs. I am a software engineer and have only rudimentary electronics knowledge with university physics. So I can understand theory of electronics better than practice.
However, I am only running the system in the range of ~2V over the stock supply. I'm hoping there are no problems.

A problem like this wouldn't show it self immediately, but would stress your capacitors and effectively shorten the lifetime of your digital controls.
***
If the caps go bad they can be replaced. Sometimes old tube amplifiers get new caps, and it makes sense when the gear is very expensive. But for the price of a black box, it would probably be easier to just buy a new one. As long as it performs for a year I wouldnt have a problem if it went bad. Actually, I found that I do not use all of the headroom and have found the most satisfying driving to be a mild boost, around 16V. I think the real advantage will be the available amperage.

I think it's worth a quick check ... just to be on the safe side

You can normally read the voltage directly on the electrolytic capacitors.
****
Some of the caps are tiny! But yes, I remember replacing some caps from my guitar wiring days.
 

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Soren Winkler Rasmussen
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QUOTE (darainbow @ 14 Dec 2004, 22:50)I would need to open the box and check the components against their specs.Yes, that's the basic idea


... but it's quite easy ... just look at the capacitors and check if they read 16V or 25V

QUOTE I am a software engineer and have only rudimentary electronics knowledge with university physics. So I can understand theory of electronics better than practice.
Well, software is the future

QUOTE However, I am only running the system in the range of ~2V over the stock supply. I'm hoping there are no problems.I think it was Lenin that once said "confidence is good, but control is better"


But anyway, it's not a big deal ... just thought I'd mention it


Søren
 

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Great info . I appreciate the detail of your explaniations. It helps idiots like me from burning my track up
Now to find a power supply so I can play Dr. Frankenstein with my Pro X.
 

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Discussion Starter · #8 ·
Sword-
Can you please explain the rating of the standard power supply?

It is listed as 17V Max (14.8V, 1450mA)

Does this mean that the voltage varies? Or that there are voltage spikes? I'm hoping that this means running the system with aftermarket power in the 15-16V range will be safe. So far no problems.

Chris
 

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Soren Winkler Rasmussen
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QUOTE (darainbow @ 15 Dec 2004, 18:35)Can you please explain the rating of the standard power supply?

It is listed as 17V Max (14.8V, 1450mA)

Does this mean that the voltage varies? Or that there are voltage spikes? I'm hoping that this means running the system with aftermarket power in the 15-16V range will be safe. So far no problems.It means that the power supply will put out 17V when there's no load on the track (cars not accelerating).

This voltage will drop when you put a load on it (i.e. drawing power = running car). That is the nature of all unregulated power supplies.

In this case it will drop to 14,8V at a 1450mA load.

When you use the big regulated power supply pictured in an earlier post, the voltage will not drop. The power supply will just increase the current to compensate for the added load. This will effectively give you more power.

If the original powersupply will put out 17V, you can safely run your track at 17V. If the electronics are dimentioned according to good engineering practice, they are at least rated at 25V. Normally you should derate this voltage by 20%, to extend the lifetime of the electronic circuit (the electrolytic capacitors are normally the weak point regarding lifetime). This means that you should be able to run your track up to 20V without problems.

Søren
 

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Discussion Starter · #10 ·
QUOTE (SWoRd @ 15 Dec 2004, 19:19)QUOTE (darainbow @ 15 Dec 2004, 18:35)Can you please explain the rating of the standard power supply?

It is listed as 17V Max (14.8V, 1450mA)

Does this mean that the voltage varies? Or that there are voltage spikes? I'm hoping that this means running the system with aftermarket power in the 15-16V range will be safe. So far no problems.It means that the power supply will put out 17V when there's no load on the track (cars not accelerating).

This voltage will drop when you put a load on it (i.e. drawing power = running car). That is the nature of all unregulated power supplies.

In this case it will drop to 14,8V at a 1450mA load.

When you use the big regulated power supply pictured in an earlier post, the voltage will not drop. The power supply will just increase the current to compensate for the added load. This will effectively give you more power.

If the original powersupply will put out 17V, you can safely run your track at 17V. If the electronics are dimentioned according to good engineering practice, they are at least rated at 25V. Normally you should derate this voltage by 20%, to extend the lifetime of the electronic circuit (the electrolytic capacitors are normally the weak point regarding lifetime). This means that you should be able to run your track up to 20V without problems.

Søren
<{POST_SNAPBACK}>


Thanks! I'll see if I have time to pop the black box open and inspect the capacitors.
 

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Another update:

The aftermarket variable power supply is ESSENTIAL for tuning the ghost cars. The ghost cars have three speeds, but with variable supply, you can get them running at any speed.

The trick with the ghost cars is not to have any R1 curves after a long straight, other wise they may deslot. My layout has R2s and R4s after the long straights and I can run the ghost cars on "fast" setting which is nice.

Also. . . At this point I have forgotten the system is digital. It has the complete feel of an analog set. WIth the rear magnet removed from the nascars and the aftermarket power, the cars have plenty of torque and they wag their tail all over the course. The special guide keel with floating magnet works quite well.
 

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Soren Winkler Rasmussen
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QUOTE (darainbow @ 16 Dec 2004, 20:08)The aftermarket variable power supply is ESSENTIAL for tuning the ghost cars. The ghost cars have three speeds, but with variable supply, you can get them running at any speed.Good idea


Here's another possibility: we build a "record-a-lap" feature into the base station, so that you could drive a car round one lap and let the base station repeat this control sequence. That way you can have one or several cars on the track with realistic acceleration and braking characteristics. The control sequence could syncronize every time a ghost car passes a sensor.

QUOTE Also. . . At this point I have forgotten the system is digital. It has the complete feel of an analog set. WIth the rear magnet removed from the nascars and the aftermarket power, the cars have plenty of torque and they wag their tail all over the course. The special guide keel with floating magnet works quite well.That's nice to hear


Søren
 

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Discussion Starter · #13 ·
Here's another possibility: we build a "record-a-lap" feature into the base station, so that you could drive a car round one lap and let the base station repeat this control sequence. That way you can have one or several cars on the track with realistic acceleration and braking characteristics. The control sequence could syncronize every time a ghost car passes a sensor.

*****
Yes, I have already thought of a way to do this in software but it would require sacrificing one of the user channels.
 

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Soren Winkler Rasmussen
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QUOTE (darainbow @ 16 Dec 2004, 21:01)Yes, I have already thought of a way to do this in software but it would require sacrificing one of the user channels.Yes, but with 16 channels, that might not be a very big sacrifice.


Søren
 

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Discussion Starter · #15 ·
QUOTE (SWoRd @ 16 Dec 2004, 21:49)QUOTE (darainbow @ 16 Dec 2004, 21:01)Yes, I have already thought of a way to do this in software but it would require sacrificing one of the user channels.Yes, but with 16 channels, that might not be a very big sacrifice.


Søren
<{POST_SNAPBACK}>

I'm talking about using the pro-X hardware with a harness between thw base unit and computer. You obviously are cooking up something very special.
 

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I have been wondering if the electronics in the power base would handle the current draw of 4 TSRF cars. It would probably be easy to place the electronics in an aftermarket chassis with hot motors. The current draw of one TSRF/Falcon motor is 3 amps at startup (this is what I'm told not measured) now lets say you hookup a LOKO PS to compensate for the added current draw but will the electronics in the power base handle the added load or will the chips in the car itself fry under the added stress or both?
I have been asked the same question of all digital systems, will an aftermarket power supply help when running hot motors?
 

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I think the answer in all cases is a theoretical 'yes' - more ampage available in the PSU will result in more ampage available to the cars. There will be a limit at which the base station and car decoder will fry (this limit will occur when the cars try to DRAW such current, not when the PSU is plugged in).

Looking at the power or current rating of the components inside may help determine what the maximum is, but depending on the circuit, not all of those components will recieve the full current/power, so this is not a sure-fire way of telling

Extra voltage is a different matter - some systems (eg Carrera) will pass this directly to the cars, others may rectify/regulate the voltage electronically, and therefor putting extra voltage at the front may not affect the cars performance.
 

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I have been wondering if the electronics in the power base would handle the current draw of 4 TSRF cars.
********

It *may* be able to handle this. The only data I have is from accelerating a car with the wheels held against the track (like full throttle run sanding). This draws the most amperage and can draw near 1.5amps based on my testing.

Additioanally I have intentionally shorted the system approximately 10 times by using a keyring across the rails. The ohmeter reads 10amps before the black box shuts down and throws its code. (I was using the 10amp outputs of the PS)

This may mean that 10amps travelled through the system. Not sure if the amperage caused the shutdown or if its the short. I didnt try this test with standard power supply, so im not 100% sure, but it looks like the capacity of the system is beyond what was intended.
 
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