Hi this is my first publication here on instructables.
While this is not a very complex project, im publishing it here first to make it available to anyone who maybe looking for a way to make a reversible current project in a easy way without needing of arduino or any micro controlled board.
This was a simply project to make a controlled toy car, with forward, backward, left and right functions, with simply switches. Thus was achieved with a 3 motors, a single DTST switch, 2 push buttons, wires and 4 AA Batteries, plus the plastic board.
Step 1: Electrical Scheme and How It Should Work
This is the general eletrical scheme. Its in portuguese, but its probably easy to understand.
In this project im using 4 AA batteries, providing a total voltage output of 6V.
Right after the batteries, there is a on-off switch that turns the whole circuit on. From there, energy flows to the the 140 ohms resistor to power up a simply led, and it goes back to neutral. The other path leads to the two directional buttons and to the DTST switch.
The DTST switch controls the back motor, that is responsible for forward/backward motion. The 2 buttons activate the two frontal motors, and thus provide right/left turning function.
Step 2: Motors Used
For this car, i used 3 motors, scrapped from old cheap toys.
In the back, i used a motor that came already with the battery box and the On/Off switch, which i used in the basic wiring. For fixing the two frontal motors, i just used a plastic piece and used 2 big screws.
Step 3: Basic On/Off Wiring
From here, in the bottom view, you can see the blue wires coming from battery contacts.
On the negative pole of the battery, i just soldered to one screw on top of plastic case. For the positive post, i soldered it to the on/off switch, and the other side of switch to the red wire, that was also soldered to another screw on the plastic case. This allowed me to have 2 basic negative and positive posts to use on the upper side of the plastic deck.
Step 4: Turning Led on and Frontal Motor Wiring
From here you can see, with the plastic top, i screwed the 2 screws providing positive and negative poles. From there, i just lay a cable, connecting to the 140 ohms resistor and to a common led, returning after to the negative pole.
Next i soldered the negative side of the front motors to the negative post on the plastic deck. Since the current on these motors will just go forward, the returning pole of these two motors will always be the same, so i can plug they to return to negative.
Step 5: Positive Wirings and DTST Wiring
For the positive wiring it was a bit more complex, because i needed to power the 3 motors, but only after passing by the switching controls. Since the DTST has always a positive pole from where the current come, i used the same wire to power up the 2 push buttons, then on these push buttons, i just soldered a wire back to the frontal motors.
The DTST switch is a switch that allows you to change the direction of a current. Its done basically with 4 poles, 2 for positive and negative from the battery, and 2 to the motors. The current flow in one or another direction, back to the switch, and back to the battery.
Check it here how to wire the DTST switch. Its really simply, and it provides 3 states: forward, backward, and off.
Step 6: All Done
The buttons were simply drilled into a plastic box. Once i set up everything, i wrapped the cables with cable organizer to make things more manageable.
One thing that i readily find with this project was that frontal left/right motors were a bad idea, because it takes a lot of distance to effectively turn the car. If you are using 2 motors to turn the car (instead of effectively turning the wheels) the best approach should be to place the directional motors on the back.
Another short come of this was project is that the car doesn't turn while going back. This was know, but it somewhat complicate things, you need to do a lot of movement to do the turning the way you want.
The best, and more clean and elegant approach is really to use an H switch to turn the current, but the proposal here was to do all this just using simply switches.