Controlling one motor with two IR receivers

[jodawill]

Is it possible to run two IR receivers so that they function together, but just receive a signal from two different angles?

I had kids playing with my train at Brickworld this weekend, and it was a bit of an annoyance for the kids that the IR receiver was only on one end of the train.

Is there a way I could use a receiver at both ends of the car without making one subject to the other?

[Zerobricks]

Hmm maybe connect the motor to another receiver using the PF extension cable?

[dr_spock]

Wouldn't be receivers be independently sending power to the motor? If one of them missed the stop button signal, it would still continue to keep the engine going?

[jtlan]

Worse, disagreement over the output voltage could damage one or both of the receivers. Hooking the output of the two receivers together is a Bad Idea.

One option might be to attach a small mirror somewhere on your loco to reflect IR signals that are coming from the other direction. You could also try raising the receiver's lens out of the loco a bit, but I suspect even then you're probably limited by the transmission range on the IR transmitter.

[jodawill]

Worse, disagreement over the output voltage could damage one or both of the receivers. Hooking the output of the two receivers together is a Bad Idea.

One option might be to attach a small mirror somewhere on your loco to reflect IR signals that are coming from the other direction. You could also try raising the receiver's lens out of the loco a bit, but I suspect even then you're probably limited by the transmission range on the IR transmitter.

I actually had the receiver completely exposed during the show. It's possible, though, that my transmitter was sending a weak signal because I had the zinc-carbon batteries in it for several months. Although they were still working fine, I threw them out after the show to prevent any problems. They're really cheap batteries.

I'm not sure whether there's a good solution to this. A mirror might look awkward. Maybe I should put the receiver on the back of the car instead of the front so they can send the signal after they miss the train coming by.

[Duq]

The light at a show is completely different from when you test at home; tube lights, no low white ceiling, and possibly other PF transmitters in the area. Not much you can do about it.

Maybe you can have a little stool or stepladder for the kids to stand on so they can aim from above?

[zephyr1934]

The PF system is set up so that you cannot connect two power sources together without deliberately modifying the path (either using a 9v jumper cable or physically modifying the PF wires). This design was deliberate to keep kids from accidentally damaging the components. Unless you are prepared to burn something out, probably best not to attempt to bypass the safety mechanisms.

Although they were still working fine, I threw them out after the show to prevent any problems.

Recycle them if possible, the acid will potentially be a pollution problem in a landfill.

The light at a show is completely different from when you test at home; tube lights, no low white ceiling, and possibly other PF transmitters in the area. Not much you can do about it.

Maybe you can have a little stool or stepladder for the kids to stand on so they can aim from above?

I would agree, though with a few additional observations. Walls and a ceiling certainly help increase the range by allowing signals to bounce back to the receiver, but I've found the range at shows is incredibly short. It is often far shorter than the distance to the walls at home. At some point I heard that the lighting in large exhibit halls typically use wavelengths that interfere with the lego IR signals (which I think Duq was getting at with his comment about the light being different).

Cheapest solution is to design a PF track layout that only needs to be controlled over a small portion of the loop of track, e.g., even if it leaves the IR range at top speed it will not fly off the tracks. One advantage to this approach is that you could actually have multiple control stations around the layout, having different kids controlling different blocks. Could be fun watching two kids ping pong back and forth. Just be careful that your train can stop suddenly while staying on the rails and go in reverse just as easily as it can go forward.

For one-person control over the entire layout there is SBrick that just had the kickstarter campaign that might solve your problem. If you are hack-savy, there is the open source bluetooth system by Codefox or other home built systems that are not documented that are probably cheaper than SBrick but more labor intensive. You could also go 9v but that is expensive if you do not already have 9v.