Aux channel switch via Losi ROSS module

[BrianG]

THe Losi ROSS remote starting system has an interesting little device that powers the starter motor and glo-plug for remote starting of a nitro engine. Well, I thought this would be a neat way to get a switched output from the ch3 slot of my radio.

The first pic is the ROSS module.



The next two pics show each side of the internal circuit board:





The blue and yellow wires normally go to the glo-plug wire, but aren't really useful for anything else. The unloaded voltage at these wires is 7.4v (using 2s lipo), but the voltage drops fast when loaded even under 1A. So I removed those wires. The red and black wires (the ones on the 4 wire harness) are the ones we want to use. The power switch was removed since these tend to be troublesome in the harsh environment of an RC vehicle. I just removed the wires, but bridged the solder pads with a small piece of wire so that it is always "on".

The finished product after modification. To retain the water-resistant feature, I covered the holes from the missing wires with a dab of hotglue:



Makes a neat little CH3 switch for whatever accessories you may want like LEDs or whatever. I've loaded the output wires with more than 5A and nothing got hot, so it can supply a decent amount of current. I wouldn't go much above that though - if you do, you could always use a relay.

Along with the switched output, the module also has a linear BEC via an LM1084 linear regulator (rated 5A). So, if you aren't using the BEC part of this thing, remove the red wire in the throttle cable.

The output is fed directly via the lipo battery, which is limited to 2s lipo. If you want to switch something that has a higher voltage, you could use a simple relay and attach a the relay coil to the output wires.

Anyway, just thought this would be an interesting little gadget to have in case someone else decides to convert a Losi vehicle that comes with this feature.