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Carrera Basic Digital to Analog switching

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  • Carrera Basic Digital to Analog switching

    This thread covers more straightforward methods of swapping between Digital and Analog. These methods generally involve using conventional analog controllers and a power supply. The graphic below is from It highlights a "normal" layout of this method, as opposed to the "lane chipping" that has it's own thread. Feel free to post any documentation you have on this

    Click image for larger version

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  • #2
    The thing that stopped me from doing this for a long time was that that you actually have to reverse the polarity of the rails to run the analog cars in the same direction as the digital cars (take a close look at slotbaer's wiring going INTO the 4PDT switch above) I also read a horror story of a failed pitlane. (Edit 20/12/19: After reading further about this I am wondering if this could have been related to the original Pro-X electronics rather than D132/D124) And so I put off this project thinking I would have to isolate the power wiring to the lanechangers, the pitlane and other accessories. But we are relying on the inbuilt polarity protection of the digital accessories. Many other people have been reporting zero issues running their Carrera digital track in this way. So I tried it for a few days and also had no issues.

    So it is my plan to make a permanent dual set up for my Carrera Digital system, also incorporating lap timing and plan to keep the timing with the Carrera digital system and your chosen RMS. I plan to document my progress and share it here. Give me a couple of weeks before I post anything further bearing in mind its nearly Christmas (i.e. very busy)

    In the mean time, for users that have an analog power base lying around, you can just swap out the two power bases and leave your lane changers in place. If you leave the single lane changers without the internal jumpering modifications, you will find that you effectively have one lane electrically. So you only need to connect the PSU to one side of the analog power base.

    Because we are talking about modifications and using equipment in a manner that was not intended by the manufacturer, my input here is informational only, and you take the responsibility for your work, and for any mishaps or failures.

    Here is also a link to a German user who cleverly incorporated the analog controllers into the CU...

    Edit 20/12/19: Noting here for historical reasons that the name "ProXudo" comes from the hobbyist Udo who first did this modification on his ProX system... His name... Udo.


    edmagner is this in line with what you had in mind for this thread?
    Last edited by Slotspeed; December 19, 2019, 11:44 PM.


    • #3
      Originally posted by Slotspeed View Post
      edmagner is this in line with what you had in mind for this thread?

      That's exactly what I was thinking for this thread..
      Thanks for helping to try and get this stuff up and organized
      Look forward to seeing your progress




      • #4
        Finally after a few weeks I have found the time to do a very basic Proxudo (dual analog/digital) conversion, possibly the simplest conversion for digital/analog use. If you already have a spare analog power base, this makes it very easy. I will follow up with more information (quite important to know what you are getting into before you start) but here are a couple of photos. I've tested it a little bit with basic accessories in place (with lane changers and wired controllers plus PC unit) and so far I am very happy with the results.

        Click image for larger version  Name:	Proxudo.png Views:	9 Size:	927.7 KB ID:	11034

        I could have built the box into a border piece, or just left it married to the original Analog power base piece, but I preferred to have a smaller box that was more easily positioned however I wanted it.

        Here is a quick look underneath. I will follow up with more details later. The outer box that the smaller terminal box is sitting on is an old case recycled from a busted old laptop power supply. There are probably more elegant boxes available from electronic component suppliers.

        Click image for larger version  Name:	Proxudo1.png Views:	9 Size:	1.13 MB ID:	11035

        Here it is with the cover off. While I had it open, I removed the wiring from the CU mainboard to the rails and upgraded to 1.5mm2 wiring to the rails (approx 16AWG) Please refer to the wiring diagram in the very first post of this thread above. I did sort the connections by polarity on the 4PDT switch rather than by lane as it made the physical wiring a little easier. Electrically it is exactly the same however.

        Click image for larger version  Name:	Proxudo2.png Views:	4 Size:	1.19 MB ID:	11145

        This is one of several ways to do it. I could have quite easily built a new box with XLR sockets and a positive path controller wiring scheme (negative rail common) rather than negative contrller path wiring (positive rail common) as per Carrera Evolution (I'm sure there is a commonly used jargon word for this but it escapes me right now) This dual use analog/digital method does not have some of the advantages of the more elaborate lane chipping method (which allows for throttle and braking adjustments). But it is the way that suited me and is probably the simplest way to get analog compatibility at the flick of a switch. It is quite important to note that it is the inbuilt polarity protection of the lane changers (and other track accessories) that allow the analog mode of operation to occur without damage to the accessories, since the analog mode of operation uses revers polarity of track rails compared to digital operation.

        Just remembered something else important - To run the two lanes independantly a modification is required on the curved lane changers, and possibly on the single lane changers (yet to confirm this)

        Early next year I will figure out a way to interface to a timing system for analog running. I did already have a go at it but the results weren't really what I had hoped for.
        Attached Files
        Last edited by Slotspeed; December 9, 2019, 06:10 PM.


        • #5
          Just a little update/addition to my last post... This afternoon I tried powering both the digital and analog control systems from the same power supply. I had no issues with this manner of powering the track control systems at all. This is by virtue of the fact that the deselected control system is isolated from the rails. Pretty neat huh?


          • D-Roy
            D-Roy commented
            Editing a comment
            Looking forward to attempt something like this once I actually get things set up. I'll be referencing this thread. Thanks!

          • Slotspeed
            Slotspeed commented
            Editing a comment
            Hi D-Roy, just be careful when it comes to the wiring... Reference the diagrams posted by Ed rather than the photo of my switch soldering. I grouped the terminals in terms of polarity because it made the soldering physically easier, but the terminals are in a different order to the diagram although electrically the result is exactly the same. Also look closely at that diagram at the polarity of the switch to the analog controller block, the required reversal for analog is implemented here. Hope that makes sense.
            Last edited by Slotspeed; April 18, 2020, 07:48 PM.

        • #6
          When talking about track wiring Analog or Digital, I'm confused about use of terms that are not clearly defined. Its been a long time and I can't remember native Analog direction of travel or wire polarity but review of a few videos online seems to indicate cars run counter-clockwise (right to left). Digital systems also have cars running right to left out of the box. Digital is considered to be Positive polarity as labeled by most online videos and experts. Why?, is left vague. Is it because Positive rails carry the current and Negative rails are common? Is it because in Digital the prime rail of a pair is the left most and it carries Positive current? Although they are very similar and either possible for naming contention, only one can be the real definition. The term "Positive polarity" is also common in Analog, does it mean the same thing?
          Since original analog hookup track and controllers have long been (8 years) replaced, I can't confirm what rails have what type of power in an analog setup, but my cars always traveled right to left. What I know as standard for Analog is based on how every layout I've had has been wired. It was wired according to instructions and with parts purchased through Professor Motor as the recommended and preferred method of track wiring for both commercial and home tracks (Positive Polarity)! We know that the car motor doesn't turn until it gets power from the rails, the direction it turns is specific to the polarity of the power on the rails to the pickup wires. When a car is placed on a track with the front facing left (direction of travel right to left) and moves in that direction, the left rail has positive polarity and the right rail is negative. My confusion exists because I already have a Positive Polarity scheme wired into my Analog track and the Cars travel right to left just like Digital.
          However, this thread mentions in several places about Standard analog wiring and the need to reverse the polarity for both systems to coexist. This makes sense if the Analog circuit is wired as Negative Polarity, but then why don't the cars run in the opposite direction? Is it as simple as correcting the concept that the common side of a circuit can be positive instead of negative? Would solve issue why cars can travel in same direction but scheme is Negative polarity vice positive.
          So what is the Polarity standard for Analog and WHY, what is the standard Polarity for Digital and WHY? Or is there no "standard wiring" for Analog or Digital just a standard for Positive or Negative Polarity. Like giving travel directions Turn Left or Right can be confused depending on direction of travel but Turn North or South is not dependent on knowing the starting point.
          SlotSpeed - "since the analog mode of operation uses revers polarity of track rails compared to digital operation", is this statement because Carrera in fact uses Negative polarity (Positive rail common) in Analog sets and it is the right side rail that is Positive not the Left as in Digital? Regardless of the logic of the discussion if I have a "positive Polarity (Left rail positive, right rail negative or common) wired Analog circuit is there a need to reverse polarity between systems or have I already accomplished that.
          Don't drink and drive but if you must... Drink Pepsi and Drive Ford


          • Slotspeed
            Slotspeed commented
            Editing a comment
            The positive rail is on the left for Digital, on the right for analog. But the car direction is the same. I suspect Carrera chose to reverse the polarity for digital because it simplifies the "analog/digital" switching arrangement on board the cars that allows the OEM decoders to be compatible with both analog and digital systems. In my opinion they should have done things differently and designed a dual system as standard. But the opposite polarity allows our trick to work. The digital accessories are protected from reverse current whilst the track polarity is reversed (for analog) because they are protected by the diodes that the track accessories have.

            Have another look at the diagram that Ed posted in the original post. It shows the polarity of each of the circuits, notice it is different each side of the switch.

            Regarding explanations and language, I try to keep it as simple as possible, the more explanation you use, the more chance someone will misinterpret it.

            Just adding... with regards to the direction of travel for digital, without thinking too hard I think the polarity is reversed at the decoder motor output.
            Last edited by Slotspeed; June 11, 2020, 03:28 AM.

        • #7
          I have finally completed Dual Wiring my track. A week in place now and after careful and constant observation convinced (from a users perspective, not electronics) that both sides of the powering and track overall are functioning as expected. That is to say as if they were two completely different tracks in two different rooms, each running straight out of the box. Of course physically they are co-mingled as one composite layout, with a single point to determine which side (analog or digital) will be powered. It is too early in the process to determine the long lasting effects of what damage if any will be done in this configuration.

          I'm not an electrician, or have an electronics background and as such only time will tell me what effects there will be. From a logical standpoint all I have done is ISOLATE the 4 power rails into 4 separate wire paths that distributes the power supplied to them from their respective controller circuits to be applied to a pair of rails for pick up and interpretation by a car. Simply stated - The power (Analog or Digital) is identical from a voltage and amperage point of view, how it is processed and passed is the difference. Analog cars do not interpret the power their motor turns at a speed according to the amount of power the controller passes and in the direction according to which side of the pair of rails has Positive current. Digital cars - Interpret the power (coded from Control Unit) as signals that contain information when decoded tells its motor how fast to turn and a bunch of other things, again direction is specific only to which contact is Pos, however that rail is specific for other Digital components to function. The point here is both systems need 2 rails per Lane or Slot path for proper operation AND these 2 rails must contain 1 Pos and 1 Neg rail for a complete circuit. The type of power voltage, amperage, analog, digital... etc. is NOT the responsibility of the Rail circuit it only passes what it is given, it is the responsibility of the Controller circuit to supply the Rail circuit with the proper type and amount

          That being said, the key to Dual wiring is Isolating the Rail circuits so that each slot path has the required Pos and Neg rail, and these circuits NEVER share with other rail pairs. That includes any crossover by any means, rail connection points between pieces of track OR internal "jumpers" within a track piece. Continuity must be priority one for EACH rail and EACH rail pair. Once each pair is isolated, the proper supply of power can be applied regardless of what type it is without consequence. That is why I stress using a 4 wire scheme (2 rails per slot path, 4 rails per track piece) each wire dedicated to a separate rail.

          I now understand why I had so much problem understanding and making the conversion. I started from a "different" analog base. "My analog" was converted 10 years ago to Positive Polarity, and considered it conventional because its all I ever knew. This was costly in time and money and could have been avoided if I paid more attention or understood why the examples found were different. The focus of polarity needing to be switched was paramount everywhere without addressing why. Having the proper polarity at the rails is paramount, having to swap it is not. As stated earlier, I'm sorry if I added to any confusion, but I do have a DUAL wired system in place and was SIMPLE to accomplish once I used the examples and feedback to guide me not follow. Should anyone be interested in how and logic behind what I did contact me or search for Pepsi Challenge Raceway on facebook. All in all, one toasted Control unit later I now have full use of my complete (over 125) Analog cars and fast growing Digital collection... at the flip of a single switch. Thanks Slotspeed and DW55 for your patience and guidance.
          Don't drink and drive but if you must... Drink Pepsi and Drive Ford


          • #8
            Ok over last couple weeks I have been noticing a couple glitches since completing the Dual wire project. Unfortunately don't know if problems are: 1) result of; 2) caused in earlier attempts (experiments); or 3) a by product of any attempt for dual wiring because of the need to isolate rail pairs vice having one wired continuous circuit.

            I know I'm late to the party and most posts discussing Dual Wiring originated back in the 2019 range. Coupled with hardware upgrades and changes, I'm not sure where I should be looking for Help and guidance. I don't have a black box, I don't Pro-X, or really know what some mean when referencing D132/D124 mode (to me its scale in digital 1/32 or 1/24). My problems are not unique in looking at past posts, but information on solving and reasoning seems lost.

            What I've discovered: Fueling problems ( specific - Fuel sensor not seen by Control Unit). Error message "Lap counter with no advanced pit"; Check Lanes (2 installed) problem (specific - sensors not seen by Control Unit). Both problems appear to be with "Sensor" operation, because of commonality. I replaced the Pit Lane Sensor track, and verified Pit Lane Entrance wiring with no change in operation. Part of this verification was checking that the Pit Lane is not being supplied by regular rails (but by Pit Circuit board in Pit Entrance track) in that the voltage on pit rail is 0.9 volt less than rest of track. I have NOT replaced either "Check Lane" but was hoping to find information on how to troubleshoot them or at least somehow test them. I have also replaced the Control Unit (to no help), and tired of purchasing new items when not sure the old is defective or needs it. Carrera is just about a dead end because they do not publish inter-workings (electronics) or operations AND just mention of DUAL wiring is taboo.

            Does anyone know how the in-track sensors operate and a way to test them? Mind you I can test and troubleshoot my Analog (DS Lightbridge) sensors and infrared sensors with a meter and cell phone camera, but no clue what values, where, or what I'm looking for in the Carrera Digital parts.
            Don't drink and drive but if you must... Drink Pepsi and Drive Ford


            • Slotspeed
              Slotspeed commented
              Editing a comment
              Did you modify both your CU's? If you have a spare CU maybe just connect your pitlane and checklanes to the spare CU and check their operation away from your layout. Or set up a small oval for testing to verify everything is working. Then go from there?

          • #9
            Yes I have modified them both by removing the internal jumpers to isolate the lanes, a MUST in my logic for Dual wiring. I did test the newest one for basic operation before modification but not with suspected sensor track pieces removed from layout (perhaps I should have). These pieces are electronic and should be able to be tested, however HOW is a challenge when you have little to no ability in interpreting what you find... if you even knew where and what to look for.
            For instance: Main power source is 0-20vdc linear power supply, output (according to internal Analog meter) is set at approx. 16v, handheld meter reads 16.12v at terminal, also at knife switch (In), Analog out and Digital Out. However displayed at panel meters (1 for each lane) at connection point to Analog side of track is 16.0 and 16.1, Digital side read by handheld meter at rails is 13.78 Ln1, 13.83 Ln2 and 12.94 on pit lane. So what does it mean? I don''t know but I think I need to add a voltage limiter circuit to the Analog side if I need to keep the Digital side supply >15 from the source. Now as for the 3+ volt drop in the Control Unit??? or is it normal, or that when referencing Digital needs 15v, it means supplied to the CU which distributes power to track not voltage at the track?. All lane changers work very well as do Start Light and Lap Counter display. Check Lanes and Fuel Stop sensors are the only things that do not appear to function, so... is it normal (+3 voltage drop) or a source for concern and possible reason sensor tracks do not have enough power to function.
            Don't drink and drive but if you must... Drink Pepsi and Drive Ford