Let's Make Robots!

Servo Advice

Hello LMRers,

I've never used Servo's nor microcontrollers in any of my robot projects, always computers, dc continuous or steppers motors, and solenoids!

So, last Christmas Santa gave me an Arduino Duemilanove (I love Santa).

Now, I'd like to get some steppers.

I was wondering general advice, shops, prices, and other considerations of my nerdy bretherin 

This seemed like pretty good prices .. http://www.hobbypartz.com/servos.html  

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..i mean use a computer as a controller, not "use a computer". ..
Also, I think there might be a difference between digital and rc servos, in that a microcontroller can't move the former. But I could very well be wrong ...
I beieve they accept the same signals but digital servos are supposed to provide more power to the motor.

Is it not true that a digital servo an be programmed to (for example) have a max speed?

 

Meanwhile we're all waiting for Grog to give us a walkthrough on using a computer.

Those servo prices seem like a screaming deal for the US. for the small ones, at least. For average or larger servos, an RC hobby shop is the place to go.

Thanks for the info Calculon320 ,

I assume the wisecrack was a wisecrack 

I posted a forum like this and noone responded. I think it depends on what country you live in to some extent. I try and buy local because delivery is quicker and cheaper. This place seems ok http://www.hobbycity.com/hobbycity/store/uh_listCategoriesAndProducts.asp?catname=Micro+Servo+0-10g&idCategory=287&ParentCat=189

noone responded cause your probably the resident expert...

I saw you have experience with the little doo-hicky that changes a dc-continuous motor into a servo  (http://letsmakerobots.com/node/2653) - and was thinking that there has to be some form of feedback

actually reading the post helps .. and you mention "feedback is still by a pot" -  So they throw you a pot with instructions "attach by any possible means to the shaft of your motor"

I really like the idea of self-contained positional feedback motor controller - but seems like setting the pot could sometimes be problematic?  How was your experience? 

The "Doo-hickey" aka "Thingey" that changes a DC motor into a servo is the same circuit found in servos but setup to drive BIG motors.

I admit that setup to convert a DC motor into a continuous rotation servo I had some problems with getting the motors to stay off. SplatBot and Mighty1 used them for this and on a cold morning they would drift backwards when they were supposed to be still. My code just turned them off. Adjusting the values of some of the components to increase the deadband should solve this problem.

I have not actually used them to convert a motor into a standard servo yet. It is only a matter of mounting the pot so the shaft is turned by the motor. The grogerpillar will be the first time.