it doesn't just short. If I unplug it after it shuts off then plug it back in with a lower voltage it won't work.

 

Here's the simple wiring that I am thinking about. Remember, I am not sure what this will do to your batteries in the long run.

View attachment 121896

And if you can use a separate battery for the light, try this.

View attachment 121897

These won't work as you have a complete circuit going through the lamp even with the switch off. You could fix that with a diode scavenged from some place.

 

These won't work as you have a complete circuit going through the lamp even with the switch off. You could fix that with a diode scavenged from some place.

Damn! Missed that. Of course you are totally correct. I'll adjust tomorrow.

Hate those sneak circuits. Ran into them a couple of times on my Modrl RR.

 

Damn! Missed that. Of course you are totally correct. I'll adjust tomorrow.

Hate those sneak circuits. Ran into them a couple of times on my Modrl RR.

Yep. That was how I learned about diodes. Was designing and installing a custom electrical system in my truck in high school and didn't know a thing about electronics and I had a ton of fuses in the control box and I wanted a panel light to indicate which ones were open and I wanted a single switch to enable or disable all of the indicators. But, of course, as soon as the switch broke the ground I had a bunch of sneak paths. Discovered the notion of a diode from the guy at Radio Shack and built a little box that I made a PCB (my first) that had a bunch of diodes and that I could fit into the interior of the box. Worked like a charm. Later, of course, I learned about LEDs that could have made things simpler, though I would then have needed the current limiting resistors and so might still have ended up with the second in-line box.

 

Came back to check on this thread, and saw that my last post didn't make it. @tyler m ! Here ya go!

 

Thanks this helped a lot! However there is one more problem. The diagram shows that the there has to be a split between the two 9 volts, however I am using a battery tray, and I can't exactly split the 9 volts. I know its oddly specific but it can't change it.

 

Yeah, I bet you can split it. There had to be a connection between the two 9V batteries. Find it and solder a feeder to it. Post pics of your battery tray from different directions.

 

Or just put a suitable resistor in series with the lamp (instead of the diode) and connect them in parallel with the motor.

 

Ahhh, there's the rub. Finding a "suitable resistor". The TS is using the engineering principle of "it just works". That is how he justifies running a 2.4V lamp at 9V! I dare to suggest that he knows not the correct voltsge of the lamp nor can he determine the current drawn. Both of which are necessary to select a "suitable resistor". I don't like my schematic either for some of the same reasons, but "it just works".

 

The suitable resistor can be found by trial and error, if nothing else. If he has two lamps he could just use one a second lamp instead of the resistor.