Reverse switch inquiry

[Madman]

So I have a Bachmann gandy dancer pump car and trailer that I have converted to battery operation. It runs very well with the exception of sprung points at turnouts. I have four turnouts that are held in place with a light spring. When normal rolling stock passes through these turnouts, all goes according to Hoyle. However the Bachmann pump car is too light to move the points and instead the points cause the pumper to derail. I experimented with adding weight to no avail. So I would like to run it on my tram line that is point to point.

So here's my question. Again, if the pump car was heavier I would install a DPDT toggle switch that would hit a trip at each end of the point to point line and reverse the unit. Since the light weight is an issue, I wonder if there might be some sort of electronic switch that would accomplish what I am after.

Here is a short clip of the unit in question.


https://youtu.be/zwEg1aqUBVw

 

[Neil Robinson]

Is it possible to fit a magnet to your Gandy Dancer? Small rare earth magnets are easily available, relatively powerful and cheap.
It could operate reed switches that would trigger a reversing relay.

One way is in this diagram, another would be to use a DPDT latching relay.

 

[Madman]

Good idea Neil, however there is not enough room for the 12 volt power supply and I am running on battery, not track power. A 9 volt battery is housed in the black box on the trailer. Some time ago, I had luck with a Bachmann streetcar. I installed a DPDT switch on the underside such that when the car reached the end of the line, a block on the track would throw the switch. The DPDT switch has a long paddle type handle that was easy to throw, plus the streetcar was heavy enough to handle the operation.

I would do something very similar here if I can find a micro DPDT switch with an easy moving paddle handle.

 

[PhilP]

Good idea Neil, however there is not enough room for the 12 volt power supply and I am running on battery, not track power. A 9 volt battery is housed in the black box on the trailer. Some time ago, I had luck with a Bachmann streetcar. I installed a DPDT switch on the underside such that when the car reached the end of the line, a block on the track would throw the switch. The DPDT switch has a long paddle type handle that was easy to throw, plus the streetcar was heavy enough to handle the operation.

I would do something very similar here if I can find a micro DPDT switch with an easy moving paddle handle.

Ok..
Change where it says 12V to 9V..
Connect the battery to where it says track power as well, and that about covers it..

You may need to use a 5V relay, and a small dropper resistor, to make it more reliable, as the battery voltage drops.

 

[Madman]

Ok..
Change where it says 12V to 9V..
Connect the battery to where it says track power as well, and that about covers it..

You may need to use a 5V relay, and a small dropper resistor, to make it more reliable, as the battery voltage drops.

Thanks Phil. So should the the 9 volt power supply for the relay circuit be a separate battery from the battery that runs the motor? Now I barely skimmed by in electronics class fifty years ago, so what is the "1N4148" and where would the small resistor, you mentioned, be placed in the wiring diagram?