I am building a dark ride at my house for a party (long story), where the I have a ride vehicle that is a wooden base with 4 casters and 2 powerchair motors hugging a center 2x6 rail on a plywood base for track. The center rail has a power bus - a strip of metal on each side for power. This all works great in a giant loop. I have multiple 24VDC power supplies connected in parallel around the track.

However, now that I have one car happily going around and around, I need to cut the center rail bus in places to make "zones" so I can add and control multiple cars at once. There will be a PLC programmed, with track sensors as input and as output a PWM to a motor controller for each zone. That allows me to control the speed in each zone differently (go fast in some cases, go slow for slowly seeing scenes in another, and STOP at the two train stations). Fast may be 24VDC, Slow 18VDC, and Stop 0VDC as examples. Slow may vary.

Here is a link to the actual motor controller:


So to repeat, I have multiple 24VDC 40A power supplies. Each one is located next to the track in different places by their respective "zone". The motor controller is connected to the power supply and the output of the motor controller is connected to the track "zone" itself. Each car on the track uses 10A while driving flat and straight and can go up to 19A when going around curves or uphill.

So HERE'S THE CRUX: If the ride vehicle crosses zones, the brushes on the vehicle that brush the center rail strips will briefly touch the strips on BOTH zones, the one it's leaving and the one it's entering. If both motor controllers are set to say 50% (12VDC), it's no concern, seems to be fine. However, I haven't tested it when one zone is set to 24VDC (full) and another say 0VDC (zero). I'm concerned about back-biasing the 0VDC motor controller. Now the motor controllers are designed to handle 60A at 24VDC (the capacitors and transisters etc.) so I am not sure if it's really a problem... and I don't see how I can solve the problem with diodes either (such as when you connect two power supplies in series).

The amount of time the brushes will be connected across two zones will be brief - maybe a second at the most???

Any help would be appreciated - I have 9 zones and I don't want to let the magic smoke out!

THANK YOU! FYI I am a cross between knowledgeable and a newbie - decent at TTL electronics etc. but not high current applications.

  • \$\begingroup\$ Is there a reason you don't put the motor controllers on the cars? That might work better... \$\endgroup\$ – ThreePhaseEel Nov 16 '17 at 23:30
  • \$\begingroup\$ Your link only takes us to the Amazon page. We probably need a link to a datasheet with a schematic. Can you find one? (Usual advice here is: no datasheet - no sale.) \$\endgroup\$ – Transistor Nov 16 '17 at 23:30
  • \$\begingroup\$ My initial thinking is that it should be OK. The only danger I can see is that the cars may speed up when both controllers are connected, faster than either controller alone. Also, it would be potentially dangerous to do this if the DC supplies were at different voltages, or if some were powered on and some powered off. Because the speed controller output is probably a MOSFET. If one DC supply were higher than another, the MOSFET body diode would conduct possibly large current from high voltage to low. But since your voltages are all the same, it seems like it will be OK. \$\endgroup\$ – mkeith Nov 17 '17 at 1:38
  • \$\begingroup\$ I can't put the motor controllers on the cars because they have no way of knowing when to slow down or speed up. That would require a data bus going around the track as well, which would be very noisy with the cars picking it up with brushes (making a connection). Even a slow serial baud rate like 300 baud seems like a bad idea on a data track, not to mention the expense... and I've already purchased the motor controllers (9). \$\endgroup\$ – Drychron Red Nov 17 '17 at 1:42
  • \$\begingroup\$ Just thinking out loud. You could have an open segment between speed zones, and come up with some other way to keep the cars moving during the transition. \$\endgroup\$ – mkeith Nov 17 '17 at 1:52

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