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Step 5Wiring Diagram
Follow these instructions if you wish to use a modified standard servo for your geared motor:
http://www.instructables.com/id/How-to-modify-a-servo-motor-for-continuous-rotatio/
If you use a Parallax continuous rotation servo there is no need to modify the gears, but you will have to modify the wiring to the servo's motor.
If you find that the motor is running in the opposite direction from what is needed, simply reverse the wires going to the motor.
tydarby posted the great graphic below, showing how wire up a modified servo . The pins to use on the micro-switch are the common (C) and normally closed (NC). Nothing should be connected to the normally open (NO) pin.
Batteries:
The parts list has a 4 AA holder but you may find that 4 batteries driving the machine makes for way too fast operation. Blink, and you'll miss it.
In most cases you should be able to get away with just 2 or 3 AA batteries, making the overall action more slower, and more visible.
Keep in mind that the Solarbotics kit only uses 2 AA batteries.
More on Motors:
I chose to use servo's because they are available almost everywhere, and are standardized, but you don't have to use one. Just about any motor should work, as long as it's geared down, and has enough torque to flip the switch.
The more salvaged parts you use, the better.
Keep in mind that another reason for using a geared motor is to prevent bounce-back from happening when the machine shuts off. Without the gearing, motor wouldn't keep the arm pressing down on the micro-switch while it's off. The machine's arm would just keep hitting the switch, turn off then on, then off, then on....
The next couple of steps show the original way I made my machine. If you're building one using the information above, then SKIP the next 4 steps and jump to step 10.
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joaca poker
That servo should work, and you'll only need to mod the wiring.
Everyone, double check your construction before putting the batteries in. When you first put in the batteries, make sure that nothing gets hot or starts to smoke.
Safety first!
Just a little clarification on the modification of the servo. If you use the suggested parallax servo, it comes with three wires attached to it, red, black, and white. These are attached to a small circuit board inside the servo housing. You'll have to take the servo apart and basically remove the circuit board and connect the red and black wires directly to the servo motor.
The instructions on how to do this are listed in the URL in step 5 on this page. It's pretty simple. Just un-solder the terminals that connect the motor to the circuit board, take out the circuit board, and connect the red and black wires directly to the motor. Done. Now you have a continuous rotation servo.
Also a little clarification on the wiring diagram. I'm somewhat of a newbie so it took me a while to get it. In the diagram, the black line running from the upper right terminal to the lower left terminal on the toggle switch is a jumper wire. Don't forget to add that one in there.
The more salvaged parts you use, the better.
Keep in mind that another reason for using a geared motor is to prevent bounce-back from happening when the machine shuts off. Without the gearing, motor wouldn't keep the arm pressing down on the micro-switch while it's off. The machines arm would just keep hitting the switch, turn off then on, then off, then on....
The straw should prevent bounce-back.
http://www.servocity.com/html/hsr-1425cr__continuous_rotatio.html