What's the best way to power motors and board?

[lloydi12345]

I would like to power my whole circuit. It is composed of 2 DC motors (toy dc motors), 1 RF transceiver that can be powered by 5v. Pic16f877a and l293d. I'm planning to have 6 pcs. of C batteries 1.5v to power the whole circuit and it will just be regulated so that 5v only can enter the micrcontroller board. Is it possible? Can you suggest other setup if mine is not so good? Thanks a lot.

Regards,
lloydi12345

 

[blueroomelectronics]

Check out my Mongoose robot. Sounds like a similar setup.

 

[ronv]

I am guessing that the motors run off of the full 9 volts? If so, your plan should work. You might want to use a LDO (low drop out) regulator to get a little more run time from your batteries before the regulator can't regulate any more.

 

[SABorn]

Yes what you are intending to do is normal, and you would use a voltage regulator to limit the voltage to 5v for the micro and tranceiver and also to the Vss pin on the L293D.
The battery voltage is connected direct to the Vs pin on the L293D.

Pete.

 

[lloydi12345]

Check out my Mongoose robot. Sounds like a similar setup.

Hi blueeroomelectronics, I have seen your robot and it looks good but mine is a lot bigger.

I am guessing that the motors run off of the full 9 volts? If so, your plan should work. You might want to use a LDO (low drop out) regulator to get a little more run time from your batteries before the regulator can't regulate any more.

Hi nice to see you again replying for my post ronv, I can't get it. I thought I should aim for low quiescent current regulators. Which is which? LDO or LQC?

Yes what you are intending to do is normal, and you would use a voltage regulator to limit the voltage to 5v for the micro and tranceiver and also to the Vss pin on the L293D.
The battery voltage is connected direct to the Vs pin on the L293D.
Pete.

Hi pete, looks like I won't have any problem with my setup.


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Adding a little information to the circuit. This is the tank that we will be controlling.
**broken link removed**

Do you think all the setup is fine? considering it's 1/15?

 

[ronv]

I guess the choice between LDO & LQC would depend on the amount of time the tank would spend with power on but not moving. If this is high the LQC might be best. But, if the batteries will be under the high load a lot the LDO will give you more time before the 5 volts goes bad.

PS. Looks like fun.

 

[lloydi12345]

So I'll go for LDO regulators? We are aiming for the tank to stay longer like maybe more than 5 hours if possible. It is carrying by the way a heavy chassis with metal threads and a wireless camera.

 

[ronv]

Ahh, a camera as well. How much current are we talking about from the +5?
Maybe something like this would save some more battery time>
**broken link removed**

 

[4pyros]

The best setup would be to have separate batterys for the motors and electronics. The motors can make losts of noise that is not good for electronics especially a RF transceiver. The a separate supply for your electronics you do not need to worry about the batterys dying and the tank going haywire and killing things. Andy

 

[blueroomelectronics]

The L293D is no match for those Mabuchi RS-380 motors. You need something that can handle 4A

 

[lloydi12345]

Ahh, a camera as well. How much current are we talking about from the +5?
Maybe something like this would save some more battery time>
**broken link removed**

Hi ronv, I don't think that's possible because there are a lot of delays happening on Ebay. Maybe another simpler option?

The best setup would be to have separate batterys for the motors and electronics. The motors can make losts of noise that is not good for electronics especially a RF transceiver. The a separate supply for your electronics you do not need to worry about the batterys dying and the tank going haywire and killing things. Andy

Hi Andy, Okay then, I think we'll be using 4 C batteries (1.5v ea) to power our motors and 4 C batteries (1.5v ea) regulating 6v to 5v for the circuit. How about this setup?

The L293D is no match for those Mabuchi RS-380 motors. You need something that can handle 4A

Hi blueroomelectronics, when we purchased the tank, the motors are not yet included. So we're buying small DC motors typically motors that can be found on tamiya racing cars. We'll be choosing high torque.

I hope you can help me finish deciding what's best. Thank you.

 

[lloydi12345]

Hi, the camera operates at 5v 2A I think we'll be having a hard time on deciding for power source

 

[lloydi12345]

Suggestion please?

 

[ronv]

To run all that you will need to spend a few pesos on some lipo batteries.

 

[bryan1]

hi Lloydi,
That does look like a fun project and I reckon this 3 amp constant current circuit I have here for my stepper motor project would be great for powering the motors. It can be made alot smaller than I make the boards and you could fit in one for each motor drive easily. The circuit uses a LM2596 along with a LM358 and 0.1ohm 5 watt resistor to sense the current needed. Although the chip is only rated around 3 amps it should be a suitable power supply. Now depending on the space inside rather than use a high speed DC motor and reduction gearbox a stepper motor could be used, maybe two for each side. Then the current requirement for the drive will be greatly reduced and that circuit of mine will easily power the steppers. Just wire up the 2 steppers on each side so they run in parallel.

Regards Bryan

 

[4pyros]

Hi Andy, Okay then, I think we'll be using 4 C batteries (1.5v ea) to power our motors and 4 C batteries (1.5v ea) regulating 6v to 5v for the circuit. How about this setup?

Thats fine, but you may be able to use smaller battrys for your electronics. You need to spec out your equpment and then pick batterys. Andy

 

[Shyamal]

nice posting

 

[lloydi12345]

Actually this project for exhibit is for our Senior Year Design Project in Computer Engineering. The preliminary project defense is the next week of the exhibit week. I am the Leader of the 3 man group and I chose this project proposal because I love robotics and same as with my members. I really find remote controlling robots cool so I really suggested this to my groupmates.

Ronv, Bryan and Andy thank you for your replies. We would like to save money and we decided to use rechargeable batteries. The problem is that we don't know yet what type of batteries we will use and what's the size. We're asked by the panel of judges to design carefully our voltage source. Ronv, I'll try to familiarize my first for LiPo batteries. Bryan, I don't think we can use stepper motors because the judges agreed already to use DC motors. I don't know if I'll be changing our L293D to L298 since it can't handle a lot current.

 

[lloydi12345]

Hi again, LiPo batteries look good. What if I'll use a LiPo battery pack for my motors maybe like 6v?, then 6v 4A panasonic lead acid battery for my camera, board and rf? I'm concerned about the noise that motors can make so I'll separate them.