[beardy56]

It's possible to do single lane with return loops in analog. Basically the the end of the loop is not connected to the track and the cars guide activates a switch as the car passes over a dead strip to reverse the tracks polarity. Have a search for rally loops or return loops in the Rally forum as well as this one, you will find a few layouts with single lane loops describing the switching and wiring involved.

 

[beardy56]

I should have said in my last post to start with the older threads from about 2012, may be even older, and work forward from there.

 

[beardy56]

You might find this link to an old thread useful. At least some of the links still work although most pictures have gone which is the same with most old posts. If you find a useful thread it may be worth checking out wayback machine website to see if they have a snapshot of the tread.

Something I did think of whist reading another thread about lap timers. You could use a optocoupler at the end of each loop, you still need a short dead strip, linked to a Adriano, or similar, and use it to switch a relay on and off. You need the double pole double throw type relays. You could probably include a lap timer at the same time.

 

[beardy56]

I would take a guess that the loop is powered separately to the main track. That way the trip switch can be anywhere in the loop. Doesn't look like there is a dead strip so I'm assuming there is either a switch in the track or an optical coupler to operate a relay. One switch would apply power to the relay for a moment causing the relay to switch the main track power direction and also be wire to power the relay at that point. A switch at the other end either in a loop or a manual switch if no second loop would cut the permanent to the relay which would switch the track power back and leave the relay in the off state. You need a relay with at least three poles and two way, one pole for each rail and on to power the relay when in the 'on' state.

 

[beardy56]

It also means that you can place a car at the start of either loop and know that the car will run in the correct direction and the main track power will be set correctly if starting at top or bottom, assuming two loops.

 

[beardy56]

You need two of these

one for each loop. Cut a hole in the side of the slot so the tab protrudes across the slot, the tab might need bending to get it to work properly with the cars guides.
You also need one of theses, 2 pole 2 way latching relay

and the wiring diagram

The micro switches are SWW1 and SW2, from power supply should read from controller. Unlike with a traditional relay that requires the power to be on to the coil to hold the relay closed and power of to be open two coil latching relays only need the coil to be activated for a momment to move the contact and it stays in that state until the other coil is activated. If we say the diagram shows the track for going from loop one to loop two the top track rail is -ve and the bottom is +ve. When the cars passes the second loop switch it is closed as the car passes activating one of the coils and, in the diagram, the contacts move down and stay there. This switches the power to the track so the top rail is now +ve with the bottom rail -ve. When the car goes around the first loop SW1 is closed for a moment and the other coil is activated, just for a moment, and moves the contacts back to the up position as shown in the diagram again reversing the power to the track. You also need two extra feed lines from the 'power supply' + and - going to each of the isolated loops. As long as the loops are designed so the car can only enter one way nothing else is needed.

If you wish you can replace the micro switches with opto-couplers but you would then need to use a micro controller board to read the coupler and activate the relay coils. This would also allow you to use a standard relay with the appropriate coding. If the cars are fitted with magnets it might also be possible to use reed switches in place of the micro switches or hall sensors in place of the opto-couplers.

 

[beardy56]

If you mean the tab at the end of the loop which I've only just noticed that may just be a sprung flipper to prevent the car from entering the loop the wrong way. The car then just pushes it open when leaving the loop and it springs back closed. You might be able to install a micro switch there but I think it would be easier to install in the side of the slot in the loop and safer. Depending on the speed of the car it could make contact with the main slot before the power has been switched and even if only for a fraction of a second that won't do the motor or gear chain a lot of good.

I made a few errors in the text description of the wiring that was here, teach me to rush so see below.

 

[beardy56]

When laying your copper tape at the start and end of each loop you need to leave a gap that will be slightly longer than the longest set of car braids.

Cut a slot in to the side of the slot in each loop. It needs to be in a fairly straight part but not to near the end of the loop if placed on the outside. If on the inside you don't need to worry so much about choosing a straight part. Install the micro switch and bend/adjust the leaver so to is across the slot and when a car passes it clears the slot and operates the switch. Repeat this for the other loop.

Start the wiring with the hardest part which is the main slot. Take the lead that would normally run to your track, from whatever power base you use, and connect the two wires to the moving contacts on the relay. The wires can either run direct or go through a connect block, the best option. Solder a jumper wire between one NC(1) contact and the other NO(2) contact. Then repeat this from the NO(1) contact to the other NC(2) contact. Then run wires from one set of NC and NO contact to the main track rails, it doesn't matter which way the wires are connected to the rails. Power up the track and make sure the wiring is working and the car runs, it doesn't matter which direction but make a note of which loop the car is running towards.

You now need to wire up the micro switches. Depending on the voltage rating of the relay coils you may be able to take power from the track power supply or you may need a separate power supply. Depending on the relay pins run a wire from the power supply to the coil common pin, if there are separate pins for each coil then add a jumper wire between the two coils and connect to one side of this. Now run a wire to common pin on each micro switch and then another wire from the pin that is live when switch is closed to the other coil pin on the relay and repeat for the other micro switch. Apply power to the relay coils and operate each switch, you should hear the relay operate each time.

The next two steps can be done direct from the power base, the connector if used or direct from the moving contacts on the relay. Assuming you have used a connector block, which makes things easier, connect two wires to the block. Run the wires to the rails of the loop that the car was running towards. Test the polarity of the loop with either a multi-meter or a car and make sure it is the same as the the main section. If it is the opposite switch the wires at the connector block. If the wiring is correct if you operate the switch in the non-wired loop you should be able to run the car along the main track and round the loop and then back up the main track. Yo can now wire up the other loop. Connect two more wires to the connector block and to the loop rails. Check the polarity is the same as the main rail when the car is running towards the loop, if not swop the wires at the connector block again. You can see why I said a connector block in the main powerbase to relay is the best option.

If all the connection are correct you should now have two powered loop and the main track should change running direction as the cars operate the micro switches. When you power the track up the best place to start a car is on one of the loops before the micro switch as this will make sure the main section has the correct polarity.

 

[beardy56]

For the base layer you can use any self adhesive copper tape but you will need a tape with conductive adhesive where the power tapes are so you would be better of buying one stating it's suitable for Scalextric Sport track as this will defiantly have a conductive adhesive, I bought mine of eBay. Power connection and taps are normally done with a machine screw (bolt with counter sunk head) or screw through the base board and you can just insert them trough the tape but it's much better to run tape over them and better still it's better to lay a small strip of tape over the hole and running each side and then putting the screw through this and then taping over the whole lot. You will at some point also need to do some repairs, and then you will need tape with a good conductive adhesive, and there's no point in not being able to use any that's left over. Having read quite a few threads a good few years ago it became quite obvious that not all tapes advertised as having conductive adhesive do or at the least have a poor conductor. You will also need a burnisher, if the track is quite flat then a wallpaper seam roller will probably work or a silicon sealant finisher works well and I'm told that plastic disposable light cases work well.

 

[beardy56]

The burnishing is needed to make sure the copper tape is suck down strongly to the board. It will also remove most of the small wrinkles you will get when laying the tape. The last thing you want is for the track to start lifting or splitting.

This is how I did my connections. Countersunk hole through the board just big enough for the machine screw head. I then laid a length of tape, about 75mm, over the hole, made a small hole in the tape and passed the machine screw through.

I then fixed the machine screw in place from underneath with a washer and nut and then attached a small power fly lead, this was done using a washer type power connector held in place with a spring washer and nut.

Once all the power connections were done I taped the track. The pictures show the small test section I did.

The wiring was then completed. I used twin core lighting wire, the type used for table lamps, with a separate colour for each lane, not a problem you need to worry about. I wired the track like a ring main with extension spurs.

 

[beardy56]

Just catching up on this one.

Timber and MDF for baseboard speak to your nearest timber or builders merchant, you won't pay DIY prices and they may be able to cut to size for you if needed. With the MDF make sure you buy the moisture resistant type but it will still need painting on all surface including any holes drilled and in the slot, don't skimp or cut corners on this if you want the MDF to survive and not warp or expand. The MR MDF is the most dense version of normal MDF and will need a good quality router bit and you will need to do the cut in a few passes. Make sure the router has a connector for a vacuum to be attached and use it. Also make sure you wear a well fitting face mask designed for fine dust, even if you do the routing outside, as you don't want to be breathing in MDF dust.

Not sure that copper tape has a conductive adhesive as the description keeps contradicting it's self. I bought mine from eBay , just do a search for copper tape for Scalextric (sport) track