# BEAM Robotics

Can someone do this using only one motor, one battery, and one contact switch please!?!?
http://www.digitizelife.com/beam/circuit1.gif
I'm a tard. I just want a circuit that will drive a motor one direction, then reverse direction when the contact is closed. NOT using an alternating switch, just a simple switch. And, ONLY using ONE battery. THANKS for the help!
John Craig <--- noob!
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Is this some kind of homework assignment?
I hope the switch is not being hit by the action of the motor,because as soon as it goes in reverse, it'll release the switch, causing it to go forward, activating the switch, etc. causing it to just vibrate at the point of switch crossover.
I'm not an expert, but I think the way you'll have to drive your motor is with multiple voltage dividers and wasting a lot of energy.
if you have 4 resistors, 2 at 1x and 2 at 2x, for example.
One side of the motor has
Power -- 1x -- leg of motor -- 2x --- ground
and the other side
Power -- 2x -- other leg of motor -- 1x -- ground
Then put your switch across the 2x resistor to ground.
You can play with varations on this theme.

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Look at the circuit on
http://www.solarbotics.net/library/circuits/driver_hbridge.html
Notice there are four "switches" in an H-bridge. By activating two of them, on diagonals you can make a motor go one way. By opening them and closing the other diagonal set, you can make the motor go the other way.
Now if you can accept that the four poles you see there can be arranged into one switch body, you can have your goals met. A double pole double throw switch (DPDT) will do the job. Pushed one way, the motor runs one direction, pushed the other way the motor runs the other. You might consider that an "alternating switch". (Not sure what that means.) So if you want a Single Pole Single Throw switch (SPST), you can use it to operate a relay with DPDT contacts on it, but you are adding one more part, and a requirement for more current when the relay was active.
Please consider what Rufus has told you as well. The motor will only reverse while the slide is in contact.
When I was a kid I had a toy cable car with this design on it. The car would run on a taught string to one end, where a long arm would push against the backstop, and throw a DPDT switch to the opposite position. This would throw the car into reverse, running back to the other side. It would remain in that state until contacting the other side with an opposing arm which pushed the switch back. And so on.
--
Randy M. Dumse
www.newmicros.com
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Well, I figured it out. The purpose of the circuit was to create a single motor BEAM with a single power source and a single touch sensor (feeler). The BEAM constantly moves forward until the feeler hits an object which causes the beam to reverse. Here is the circuit;
http://www.digitizelife.com/beam/circuit2.gif
Thanks for the e-mail help and posts! I'll post pictures when it is made. Hopefully tonight it'll be together. Here's a drawing for now;
http://www.digitizelife.com/beam/bob/bob_drawing.gif
John Craig
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Get some current limiting resistors, maybe a couple hundred ohms each, in those base legs, of you'll over current the bases and burn out the transistors.
You may need to add clamping resistors to keep the off transistors really off. Clamping resistors go from the base to the emiter of the transistors (and come after the current limiting resistors). Usually, the values are a few thousand ohms.
--
Randy M. Dumse
www.newmicros.com
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