Skid steer wiring.

[Spandy]

I have made a wired robot using two DPDT switches. One for controlling motors on each side of the bot. But it becomes difficult to control the bot in a straight line. So I want a switch to control forward an d backward movement while another one is used to turn the bot. But I cannot make the circuit work as the battery is getting shorted. Any suggestions?
Thanks in advance 

[Spandy]

Any suggestion??

[Conscripted]

You could use one switch to controll the forward/backward movement for both motors. Use two other switches to break the connection for one motor or the other. This would give you the ability to stop one motor and the other would continue. I.E. remove power from the left motor to turn left. In this configuration you would not be shorting the battery. It will make the wiring a little more complicated but it's not to hard.

Conscripted

[Spandy]

thanx a lot for the reply
but, i have made such a circuit....wat i wanted to ask was does there exist such a circuit where while turning the wheels on either side would move in the opposite direction?..........
hope u would help me out again  

[Soeren]

thanx a lot for the reply
but, i have made such a circuit....wat i wanted to ask was does there exist such a circuit where while turning the wheels on either side would move in the opposite direction?..........
hope u would help me out again  

I think you have to rephrase that, because that's exactly what Conscripted told you how to do.
Don't be afraid to use too many words, better be thorough in your explanation than be misunderstood.

[knossos]

I think what he means is that instead of stopping the second motor, you reverse the second motor.  Kind of like the steering on a beetle bot.

[Soeren]

Hi,

I think what he means is that instead of stopping the second motor, you reverse the second motor.  Kind of like the steering on a beetle bot.

Aha, yes that makes sense rereading it with fresh eyes - thanks.
That would give a major jerk, suddenly reversing one motor when moving ahead.

[lastRites]

Yes, but since we are using 200 rpm motors, the bot would not be fast. So jerking is not a problem. I have already made a circuit that can stop either motor while moving forwards or backwards, thus turning the bot. But the turning radius is a bit more than what is required. So I need both motors to move in opposite directions to facilitate a sharper and faster turn. Is this circuit possible using DTDP switches and wires?

[knossos]

So I need both motors to move in opposite directions to facilitate a sharper and faster turn. Is this circuit possible using DTDP switches and wires?

Did you look at the Beetlebot link from my earlier post?  It does exactly that.

[lastRites]

So I need both motors to move in opposite directions to facilitate a sharper and faster turn. Is this circuit possible using DTDP switches and wires?

Did you look at the Beetlebot link from my earlier post?  It does exactly that.

Thank you 
Yes I have seen the beetle bot. But if I want to adapt this circuit to our bot we will need two voltage sources of 12 volt each. Right? But the nature of the circuit prevents us from using our voltage source (pc smps) as it would short it out. Even if we manage to get some other source would it be possible to get the bot to move forward or backward in a straight line cos we have to navigate the bot precisely.  I have another idea that might solve this problem mechanically. This may be done by using 2 pairs of DPDT switches, 2 identically wired switches for each side of the bot. I mechanically connect 2 switches of either side together such that when I push a switch both get depressed.  Now if I make two such pairs such that one pair moves the bot forward (both switches in identical orientation ) and the other pair moves it clockwise or counter-clockwise(one switch inverted) would it work??

[Soeren]

Hi,

Did you consider throwing in some relays?
Then you could get the switches down to a 3-position switch for forward-off-back and 2 single pole push-buttons or SPST switches for turn-left and turn-right.

[lastRites]

I don't know how to use relays Can you please explain how to use them? Can they handle currents upto 15 amps?
 

[Conscripted]

A relay is basically a switch controlled by an electro magnet. Finding a relay to handle 15 amps should not be hard. Automotive relay's are rated at 12v and work with that kind of power some times.

http://lmgtfy.com/?q=how+to+use+a+relay

Good luck.

[Soeren]

Hi,

I don't know how to use relays Can you please explain how to use them? Can they handle currents upto 15 amps?

Lots of info on the net on relays, Here is a good tutorial on the subject.
Relays come in a multitude of current ratings.

Here is a wiring diagram
Forgot to mention the 12 diodes you'd need, but I gather that you wish to make it non-electronic due to lack of knowledge(?) of how to do it, but diodes are very easy to use.
Their purpose is: D1 to D4 are for protection of the switches against inductive kick back from the relays and D5 to D12 constitutes what is called diode logic, that routes the switches outputs to the correct relays.

It will take two switches with each 3 positions (single pole though) and if wired as shown, should work as you specified. Remember to add a fuse in the +12V line from the battery.

SW1 could be one with a spring return to the center position.
SW2 could be a 2 pole switch with center position off.

[lastRites]

Thanks! I will try this ASAP

[SickSpeedMonte]

There is a company called "Help!" (aka Motormite) that sells 30A SPST relays in any auto parts store.  They are like $4 and change/ea.  Calterm makes them too, as well as Bosch, and alot of people snatch them out of cars in pull-a-part yards when they go for other car parts. 

[Gualalasmooth]

Check out this control with relays I think this one works great Its about servos micro switches and relays

http://www.squidoo.com/diy-robots-