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Offline Fiery DuckTopic starter

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First Robot
« on: March 01, 2010, 09:55:35 PM »
I'm using the 50$ robot tutorial for my first robot. I have parts from a VCR/DVD player combo that broke. I have 5 dc motors, 2 the same size, the rest assorted. I was thinking of using the motors, but how would I control them? Do I just plug them into the microcontroller? They are 5.9 volt and have a black wire and red wire coming out of them. Help a newb! ;D

Offline SmAsH

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Re: First Robot
« Reply #1 on: March 02, 2010, 12:05:39 AM »
Well, that depends whether you want to buy a new microcontroller?
Dc motors pull too much current, mcu pins can supply ~40mA of current, dc motors draw heaps more.
You will either have to:
1. Buy a motor controller to control the motors (requires code modifications)
2. Buy the servos.
Also note, the dc motors may be too fast, not powerful enough etc... I would go with the servos...
Howdy

Offline waltr

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Re: First Robot
« Reply #2 on: March 02, 2010, 10:28:48 AM »
You can learn a lot from the VCR parts and there is a SoR tutorials on using VCR parts.

Here is a list of tutorials with lots of great ideas:
http://www.societyofrobots.com/member_tutorials/
And the VCR robot:
http://www.societyofrobots.com/member_tutorials/taxonomy/term/9

Offline Fiery DuckTopic starter

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Re: First Robot
« Reply #3 on: March 02, 2010, 05:32:35 PM »
Couldn't I use an H bridge? My robot book has schematics for it...but the electronic side is lost to me.(Thats why I like the idea of using roboduino on my robots) So, could anybody help me with the H bridge?

Offline waltr

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Re: First Robot
« Reply #4 on: March 02, 2010, 07:14:01 PM »
Yes, you could build your own H-bridge. There are many designs on the web to be found.

My point is that you can get started with very little and you will learn.

Offline HDA

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Re: First Robot
« Reply #5 on: March 03, 2010, 02:32:21 AM »
Hi,
Good news you have some importants parts for your future robot !
First of all read this Tito : http://www..com/schematics_Hebrides.HTML
& then you could use  L293D for integrated H bridge for a few € ($) : it's very simple to use it read datasheet from the web.
 ::)

Offline SmAsH

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Re: First Robot
« Reply #6 on: March 03, 2010, 03:08:18 AM »
Your link appears wrong sir?
Howdy

Offline HDA

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Re: First Robot
« Reply #7 on: March 03, 2010, 03:32:33 AM »

Offline Fiery DuckTopic starter

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Re: First Robot
« Reply #8 on: March 03, 2010, 05:33:49 PM »
I've read the article, but what is a L293D? Is it some kind of IC? :-\

Offline SmAsH

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Re: First Robot
« Reply #9 on: March 03, 2010, 06:17:04 PM »
Howdy

Offline Fiery DuckTopic starter

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Re: First Robot
« Reply #10 on: March 03, 2010, 07:22:07 PM »
Okay, so where does it go? I think I misunderstand because the diagram looks like a basic H-bridge.(sorry for all the questions. Electronics are ...hard for me to understand.)

Offline Razor Concepts

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Re: First Robot
« Reply #11 on: March 03, 2010, 07:25:35 PM »

Offline Fiery DuckTopic starter

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Re: First Robot
« Reply #12 on: March 03, 2010, 08:21:29 PM »
I found this on the internet.

What does it do?

The L293D driver subsystem is particularly useful for use with d.c. motors because it can control two motors and can drive them forwards and backwards.   



How does it operate?


L293D driver circuit

Click on the circuit diagram to download a Livewire file of the circuit that you can investigate and add to your own circuit.
 The L293D IC has four input signals, labeled ‘a’, ‘b’, ‘c’ and ‘d’.

The driver boosts the current from these signals. The voltage signal at each output (‘a’, ‘b’, ‘c’ and ‘d’) is high or low when the corresponding input signal is high or low. But the current available from the output pin is much higher.

So the L293D is able to drive output devices requiring quite high currents of up to 600mA from each output pin.

The main advantage of the L293D is that, unlike a transistor, Darlington driver or MOSFET, it can drive a d.c. motor in forward or reverse.

It is particularly useful for work with PICs (hotlink to data sheet).

As well as controlling d.c. motors it is useful for work with stepper motors.
 

 
If the L293D is connected to two d.c. motors as shown on the left, and input signal ‘a’ is high and input signal ‘b’ is low, then current will flow out of output pin ‘a’, through the upper motor and into output pin ‘b’.

If input signal ‘c’ is low and input signal ‘d’ is high, then current will flow out of output pin ‘d’, through the lower motor and into output pin ‘c’. So the current in the lower motor will flow in the opposite direction to the current in the upper motor, and the motors will rotate in opposite directions.

Current can only flow in one direction (the direction of the arrow on the circuit symbol) through a transistor, Darlington driver or n-channel MOSFET, – which is why they cannot be used to reverse a motor.
 

When current is flowing out of the L293D this is called ‘sourcing’. When current is flowing into the L293D this is called ‘sinking’



So when I plug something into one side I need to plug the corresponding wire into the opposite thing on the otherside. Sorry if that sounds really dumb.

Offline waltr

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Re: First Robot
« Reply #13 on: March 03, 2010, 09:31:50 PM »
There is an SoR tutorial that uses the L293 here:
http://www.societyofrobots.com/member_tutorials/node/62

Its a popular H-bridge and there is an lot of info around. Did you try googling L283?

Offline Fiery DuckTopic starter

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Re: First Robot
« Reply #14 on: March 04, 2010, 05:51:38 PM »
I'll look up L283 real quick.

Offline waltr

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Re: First Robot
« Reply #15 on: March 04, 2010, 07:39:50 PM »
I'll look up L283 real quick.

Aaaa...Hop you don't take my typo seriously. It should be L293.....

Offline Fiery DuckTopic starter

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Re: First Robot
« Reply #16 on: March 04, 2010, 07:41:42 PM »
No wonder anything came up... :P

I also found this website:http://www.toddholoubek.com/classes/pcomp/?page_id=394
Can I do this without using a switch?
« Last Edit: March 04, 2010, 07:50:36 PM by Fiery Duck »

 


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