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SARC Pro - digital layout

Dr_C

296 posts

Hi all, this modification is moving along the right lines (in my opinion), BUT still absolutely not recommended (in my opinion). This is because at the point of the cut, there will be opposite signal polarities on each side of the cut line. This configuration will result in a short circuit occuring briefly each time a car’s pick-up brush traverses the cut line. Given the power base can provide approv 8 amps of current, this will generate quite a sizeable spark each time. This will be bad for at least two, possibly three, reasons.

1/ it may affect nearby rf comms (sparks are broadband rf noise)

2/ the short circuit which occurs every time will be trying to put the ARC PRO into safe mode albeit briefly each time. This may cause long term damage, or premature failure, of the ARC PRO drive circuits) and worst case senario some blue smoke...

From a design piont of view I would strongly advise against this configuration... albeit that it appears on the surface to work in a satisfactory way in the short term.

If you don’t believe me - briefly try driving cars (with no lights) over the cut line in a darkened room - and watch out for the sparks... the sparks will be generated by 8 amps current at 15 volts...!

C

 

 

 

 The change lane gets powered from the flexible circuit boards from the track 2. You won't get any short circuit, because the flipper is not connected with power, and when you cut the track 10mm or 15mm therefore will be no short circuit from the car’s pick-up brush. I was plying today over 3 houers with no problems.

Dr_C

296 posts

Hi Josef,

i believe you are misunderstanding where the short circuit is likely to occur. The flipper is not relevant all all. The short circuit will occur on the rail next to the flipper precisely where you put the cut. Your cut is I am sure intended to separate two track signals which are pulling in opposite directions I.e. the full 15V switched signal will be present across the cut line at all times. When the car brush passes over the cut the two sides of the cut line will be ‘bridged’ i.e. a full current serious short circuit. If you don’t believe me, move the car very slowly by hand (no throttle power) across the cut line and watch the ARC PRO go into SAFE mode. You are stressing the system every time you drive over the single cut line. Really not a good idea!

If you are planning two cuts, 10-15mm apart that would be fine - but that’s not what you are showing in the photos, hence my concern.

C

gorp

611 posts

is your lane 2 the receiving lane ?

gorp

611 posts

Josef,

Still confused here.

Does your car leave lane 1 to go to lane 2 ?

Which lane is powering the space between lane 1 and lane 2 ?

gorp

Dr_C

296 posts

Just to re-iterate... two cuts is far better than one! Please see photo above noting cuts in front of little mini... and please see more details under blagard-01's thread in the ARC PRO subject area of this forum.

gorp

611 posts

find blagard's curved changer mod at arc app race control forum ,

not here on digital forum

@josef_ineichen

Hello i am from Switzerland, and sorry my english is not so good. The first step was to open the clamp, remove the leads, and close the clamps again. Put a sticker over the clamp for any short circuit. Then remove the rail and cut it with a angle grinder clean the ends and put it back on. Do it the same thing on the next curved lane changer and now it works Analog and Digital. Good Luck.

 

Dr_C

296 posts

Thanks Josef for sharing these photos and also the ones where you show how you modify the flexible pcb tracks (i.e. by removing from the clamps then insulating using cellotape/scotchtape).

The photos are great and really show the practicality of modifying the curved lane changers.

 

My thoughts are:

 

1/ remember you need to make the cut gap much wider (e.g. 10-15mm£ to avoid unnecessary short circuits as the brush crosses the gap) otherwise you will be creating lots of radio frequency interference (remember the purpose of monsieur 'ferrite'), unnecessary sparking and unnecessary stressing of the ARC PRO overload mode!

 

2/ I really really like the cellotape/scotchtape idea you show in your photos. Based on your posts I did the standard 'digital-to-analog' mods on my eight pristine curved lane changers without a single 'snip'... I used pvc tape but otherwise the same as I learned from your photos. Modifying all eight curved changers took just 1/2 hour. Thanks for the amazing 'steer'!!!

 

Finally, I genuinely hope the photo I posted with the little mini approaching a DOUBLE cut ( which introduces a 10-12mm dead zone) causes you to re-visit the appropriate size of the gap in your design approach. Take care,

 

C

gorp

611 posts

glad to see you are discussing pics not shown on this discussion

 

since  josef did not answer question concerning which lane is powering middle , cannot comment on his mod but do know blagards is good idea

 

how long does it take you to snip snip ?

is there any reason you would not want to snip ?

 

 btw just curious , but do you think you are running this discusion now, since you just dismissed josef ?

 

 

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