Let's Make Robots!

DAGU Promotion, Cheap HW, LMR Mr. Basic Special LMR version + 3 prizes!

Update: --== DAGU ROCKS ==--


Update: NEW manual attached! Replacing old one. Sorry for the format, PDF was too heavy :)


 Hi dear fellow robot builders, members of LMR.

As I am sure you know, OddBot has made us some cool contact with Jack from China, the guy behind DAGU Electronics.

Now I also had some talks with Jack himself regarding a production of some of my stuff (Thanks Odd).

And I tell you, the guys at DAGU moves fast, sends money as promised, and the hardware is actually REALLY NICE! 

And I am NOT just saying this because he is supporting us, I have tried quite a lot of HW that people wanted me to promote on LMR, and it was not all that good ;)

However - now I just got this cool mail from he’s assistant, Claudia:

Dear Frits,
How about these days?
This time I'll show you a great kit, named Mr. Basic, consisting of a aluminum alloy chassis with an extension PCB, which provides a reliable expand platform for DO-IT-YOURSELF. You can find the photos of it in attached files.
So far, we just have Chinese package for Mr. Basic, but there are English user manuals, so everybody can assemble it with his own hands depending on the manuals.
For Chinese market, our original idea is letting all robot hobbyists can create their own robots with our Mr.Basic.So Jack thinks this product will also be a good choice for the members from LMR.
We are excited about your idea about "LMR members editon", so we would like to offer 50 sets Mr. Basic printed with LMR logo with a special price only for LMR members, it just cost them 22USD($15 per set and another $ 7 for shipment) to own one. Every member who bought one and designed a new variation can put their creatures on LMR, and you can let other members and users vote out three best ones, each winner will be offered $100 from DAGU as prize.
What do you think about the above idea? Hopefully waiting for your respond.
Kind Regards,
Claudia

 

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This is cool!! Those things are almost like free at that price! And it is our first real LMR merchandise! :)

What you need to do to participate:

  1. Send a mail with your order (and address) to Claudia:

    claudiadagu at yahoo.com.cn

    Let the subject of the mail be "
    LMR Mr Basic" She will return to you, be fast, only 50 made.

  2. If you feel like using your Mr Basic Special LMR-version for more than a mantelpiece, then make some robot out of it. Submit it as a robot on LMR.

  3. IMPORTANT: TO make sure that you participate in the competition, you must add the tag “LMR DAGU Contest” to the posting.

  4. Vote for your own robot. (I know you are going to do so anyway) - But also; Vote for other robots that you think should win!

  5. Wait for everyone to be finished and cross your fingers :) We make a special page for this, with all participating robots, and the 3 robots voted highest will each win the price of USD 100!


Yes!

 

PS: Since this is going to be won by robots only seen on the page, good images matters as well as cool robots. I just know from experience. For inspiration, see this that I wrote once :) (The part about taking good pictures)

PPS: Thank you OddBot, Jack, Claudia, and DAGU! Nice going! :D

PPPS: You are a very competent person.

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He's a speedy little bugger he is. And that with rechargeable batteries (3.6V). We're definitely gonna need PWM on this one. 
For an h-bridge, the Pololu Low Voltage Dual serial looks like it should work.
Isn't that one a bit expensive? I wonder if the good old L293D will be sufficient. Or do these motors draw too much current?

My motor (I measured just one) draws current from 3.85 V source as follows.

free running: 230 mA
working hard: 1000 mA (I smell brushes heating up!)
stalled: 2570 mA

I will probably use a L298N and add two extra batteries. This will give me 6V (5x 1.2V) for servos and the ideal voltage for a LM2940 +5V low dropout regulator.
That seems to point to them being  RE-260RA-2295, seems pretty close. I don't know if these little motors respond very well to PWM changes, so unsure if h-bridge or relay would be better.

Hi robologist,

I tried hooking them up to a L293NE driver chip which can handle 1A cont. and 2A peak per motor and let the motors run at 50% duty cycle while holding the car up in the air. I was figuring that the motors would not draw too much current then. I set PWM at 15 KHz but nothing happened (verified the 15KHz with my multimeter). I set PWM to 100% duty cycle (or at least VERY close to 100%) and then one side of the wheels started turning somewhat strangely. They would spin for a quarter of a second or so and would stop for a quarter of a second and continue like that - and the L293 would start to heat up :-). Can this be related to the motors not liking PWM, you think? Or is it just the L293 choking?

Two possible causes

1. the voltage dropped by the chip doesn't leave enough to drive the motor. You probably need at least 6V if you are using one of those motor driver ICs.

2. The motor has an inductive reactance, try lower frquencies to reduce that.

 

I would also put a 0.1 uF cap across each motor to absorb some electrical noise and ensure the motor control IC has a good filtered supply.

Thank for the reply, OddBot.

I'm using a separate 9V battery through a LM7805 regulator (22uF cap on the "inside" and 2.2uF on the "outside") for the brains (an ATtiny26 and a L293NE) and the L293 has its VCC1 (the supply pin) connected to 5V and its VCC2 (the motor voltage) connected to the 4.5V from the 3 AA battery clip. It seems from the motor datasheet that 3V (4.5V minus the drop in the L293) should be more than enough to run the motors off. The 9V and the 3 AA battery clip share common ground.

I will try lowering the PWM frequency and adding caps.