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Servo and picaxe: need resistor ?

hello, i'm trying to use a servo with my picaxe. I tried it on Arduino before, and it worked just connecting the pins at the right position, without resistors.

now i just connected the same way on the picaxe, and it doesn't move.. I then remembered that in the "start here" project, a resistor was used.. So the question is: is it necessary? why do i need a resistor? and how do i wire it ?

Another thing that is probably messing up.. i have the darlington chip there.. shoud i remove it?

 

thanks :) 

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Well, in general, resistor would be needed to reduce current through/voltage on the servo. May be servo internal resistance is usually small, which implies a current which might be too stong for either MCU or the servo itself... so it would make a lot of sense to put some resistor there just to reduce the current. TTL high level is 5V, if Rservo is measured in single digit Ohms, current strength would be in Amperes (rather than milliamperes)... can be disastrous for the chip, I guess.
I told you; No one knows why, but just add it ;D

Uh, well, as a certified "arty" I can tell you now, that even if "no one knows why", you can figure it out. ;) All you need is knowledge of Ohm's Law and reading MCU and servo specs. It's way simpler than "FritsLDR", seriously... :D

 

 

O.K. Peter,

Can we not be so serious here?  I think that what frits was trying to say was "just use a 330 ohm resistor".

I know Ohm's law.  Very well.  And I feel sure that frits does also.  But I also know that there is no way that I could ever explain it in other than my native language. 

If you want to post a walk-thru of Ohms Law  (in English or Danish ) then please feel free to do so.  Or if you'd like, an explaination of EMS. 

Most of the people here do not have Electrical Engineering degrees, or even any experience in electronics.  They are here as hobbyists,  and just want to know how to solve a problem.

Best regards, 

Duane S

Wilson, North Carolina  USA

Just for the record; I do not know Ohms law.

I tell you all because if someone out there is like me, I want to send the messege; You do not have to know it t have fun. I know no electronics.

Ha Ha Ha !  Well, you've certainly fooled me.

You do make a very good point.  One does not have to be an electronics Guru to have fun with electronics.

Duane S

Wilson, North Carolina  USA

...I'm just not telling you because the last time I told you how something works you called me bad names like "techie" and stuff. Besides I don't want to spoil the illusion that it all hangs together by magic.

Oh, and another thing: Santa Claus is REAL. Don't let anyone tell you otherwise.

Real? I always declare him an integer. Way more efficient.

C'mon, BOA,

Everyone KNOWS that Santa Claus is real.  As are the Easter Bunny, and the Tooth Fairy.

They have been discussed over and over, everywhere on the internet.  It has been firmly established that they are real.

So, please don't drag Santa into this again.  He's very busy this time of the year.

Everything electronic is based on EMS.  To doubt that is to challenge it.  Thomas Edison tried to challange it, but gave up.


Like most of us, you apparently do not fully understand EMS.  Fortunately, EMS does not need to be fully understood to use it.

We all use it every day, but very few of us fully understand it.  Instead, we appreciate it for what it is, and use it as best we

can. 

Duane S

Wilson, North Carolina  USA

Sorry if it ever came out wrong; "techie" is NOT a bad thing to be! Us artys would be nowhere without you. Absolutely! You are the key!