switches How to Build an Auto-Reverse HO Trolley Circuit

by:Leimove     2020-03-12

I think it would be cool in my HO scale train layout to get a trolley across the city center.I want the trolley to go through the city center and when it gets to both ends of the line it stops to reverse, but I don't know how to do that.How do I control the movement of the trolley, have it stop in the city center for a while, then continue to the end of the line, pause, and go back in the opposite direction?Also, how do I determine where the tram is on the track?At first I wanted to use a circuit that uses a PIC micro-controller to perform the required logic, but then I decided to do the job with a simple transistor circuit.I came up with the idea of using reed switches and magnets to determine the position of the trolley on the track.The reed switch is connected to the track at both ends of the tram line, one in the center.The magnet at the bottom of the trolley causes the reed switch to turn off when it is directly on the reed switch.Below is a picture of the magnet at the bottom of the trolley that activates the reed switch.I took the magnets out of the Playskool alphabet and stuck them to the bottom of the cart.The circuit consists of two PNP transistors that make up a bi-stable circuit.When the magnetic sheet switch connected to both ends of the track is activated and the magnet on the trolley closes the circuit, the bipolar circuit changes the state.A transistor of a bi-stable circuit is connected to the drive transistor.This activates a relay that changes the direction of the trolley by changing the polarity of the voltage on the track.There is also another circuit consisting of a 555 timer integrated circuit, which is suspended whenever the trolley changes direction and is located in the city center.The 555 timer integrated circuit is connected to the second relay that interrupts the power supply to the track and causes the trolley to stop.555 when the timer integrated circuit is activated, the change of the state of the bistability circuit is automaticInstead, or when the reed switch in the center part of the tram track is activated.The auto-The reverse trolley circuit is powered by AC terminals on the model railway power supply.A bridge rectifier circuit and capacitor that corrects and filters the AC current into a relatively stable DC current.The 7805 regulator then adjusts the voltage to a stable 5 V.The DC terminals on the model railway power supply provide power to the trolley through the track, and the polarity of the track voltage is switched by the automatic relayReverse circuit.This is an automatic schematic of my trolley.Reverse circuit.I used led (LEDs) in this circuit to indicate the status of the bipolar circuit.Build this track at your own risk!I am not responsible if you have burned your train model power supply, the motor on the trolley, or damaged you or your track.You should have basic knowledge of electronics and electricity before building a carReverse HO trolley circuit.Bread on the carI built power for the car.Reverse HO trolley circuit on a separate weldable performance board.Because the design is direct, there is no need for wiring in this part of the circuit.I got the rest of the car on my bread.Reverse HO trolley circuit so I can change the circuit dynamically if needed.I always recommend that the bread be put on the untested circuit design before submitting to the weldable performance board.Next I set up a test track next to the workbench so I can test autoReverse HO trolley circuit.This makes it easy for me to make changes dynamically without affecting the HO scale layout.My automated test is complete.The reverse HO Tram circuit is like a charm.It's time to add it to my HO scale layout.The first thing I did was to add the reed switch to both ends and center of the trolley track.I suggest you install the reed switch on the rail before you install it on the layout so you don't get hot glue and welding on the layout.I then weld the track parts together so they don't loose during operation.Be careful not to weld at the top or inside of the track, as welding in these areas may derail your trolley.I used a few 2x4 pieces of wood to lift to the tram track so it was easier to assemble.I am wiring the wires that will be attached to the reed switch along one side of the track.The very thin black line I picked up in my hobby shop is attached to the reed switch.I can connect the magnetic sheet switch with very thin wires because the current of these wires is very small, less than 1 mA.I put the tram track through the center of my layout and all the wires exit on the right side of the track.I drill holes in the plastic ballast section of the rail track so that I can wire through these holes to have the ballast flush with the table.I need to keep my HO layout easy to disassemble in case I need to move it.Automatic installation of trolleyVehicle Train power supply, automaticThe reverse Circuit and the power perf board are installed on the console of my HO layout.Make sure to install the model train power supply so you can easily adjust the speed of your car.The trolley can run now!It will pause in the city center, then move to the end of the track, then pause, then return in the opposite direction, pause again in the city center, and then travel to the end of the track in another direction, pause and reverse again.Video of auto-The reverse car is moving!This is the video of my trolley running on my HO layout.What if I want the trolley to stop for more than one stop?Just add more reed switches in parallel with the reed switch sw2.Place the added reed switch in the desired position on the trolley rail.With some basic electronic knowledge and wiring skills, you can also have a working trolley system in HO layout.
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