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Currently I'm doing a project where I am simply trying to get a robot to move forward without code by using say a push button or a potentiometer. I plan on moving on to micro controller later, but right now I'm trying to work with my first perfboards and soldering irons. It has 4 DC motors, each with a free current of about .4A and a stall of 5A, but I don't really know how to hookup the circuit correctly. Each motor uses about 7 volts. I was wondering a.) Is there any specific way I should construct motor b.) What type of battery should I use to power the circuit saftely

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  • \$\begingroup\$ Do your motors ever have to move at the same time? \$\endgroup\$ – Dwayne Reid Apr 29 '15 at 2:21
  • \$\begingroup\$ Yes- all at once \$\endgroup\$ – Enthurzan Nov 6 '15 at 3:40
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I would start off with an old drill battery pack and maybe even the drill speed control. An old 9.6V Makita or DeWalt drill would work well.

The advantage of using a decently-sized battery pack from a battery drill is that you have both the battery and charger. These battery packs are generally 1.2 - 2.0 Amp-Hours and can supply really significant amounts of current for short periods of time.

You will need 8 wires going from your controller to the robot. These should be fairly beefy - I'm going to suggest 18 AWG if the cable is long (10 feet) or 20 AWG if the cable is short (5 feet or less). 8 conductor 20 AWG rotor cable works well and is inexpensive. Black polyethylene jacket, conductors have PVC insulation. Available from lots of places.

Your control box will have 4- DPDT center-off switches and a push-button. The DPDT switches are easy - you can use mini-toggle switches or full-size switches. The full-size switches can handle more current but the mini-toggles will be okay so long as you don't move them while the motors are energized.

The push-button is more of a problem. Most of the hobby-grade buttons can't handle any significant current. However, there are lots of automotive switches that are beefy and readily available. Head over to your friendly automotive parts store and ask the counter people for a rugged momentary push-button switch.

You will wire all 4 DPDT switches to have a reverse function. Power to all of the switches comes through the push-button from the drill battery pack.

Simple schematic diagram follows:

schematic

simulate this circuit – Schematic created using CircuitLab

To use this, set all of the motor switches OFF except for the motors that you want to use. Then press the button for as long as needed. Let go of the button, change the motor switches, then press the button again.

Have fun!

Come back when you are ready to add some electronics to this.

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