Let's Make Robots!

Help with servo

hi, first of all: sorry, my english is so bad. and I mean .. BAD. 

I am a beginner, and I have some problems with servo controller! I fallowed "how to make your first robot" by fritsl (great fritsl..!!), except I used a srf05 not a ir sharp sensor device. (there's an other problem, I connected srf05 like http://letsmakerobots.com/node/66 but I can't insert a functionally command string in the fritsl's program that let it work, although it seems to work with the node 66's code)

I connected the servo using a standard servo connection (soldering an extra pin to output 0)

When I upload "servo 0, xxx" the servo does nothing. When I disconnect it from the picaxe 28x1 and than connect it again it takes a little turn. When I upload the program of the fristl guide the gear motors go on, but the servo turns on its right, than takes a pause.. than turns on its right again, and so on.. and so on.

I supposed that the problem is that I don't bought PICAXE servo upgrade pack and I haven't the "yellow chip", SO I LEFT THE DARLINGTON-DRIVER IN .. .. but I can't figurate out what the "yellow chip" is and I can't say its name to the electronic's shop! .. .. I don't understand what is the function of this yellow chip too..

 could you help please? thanks all.. 


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This yellow chip is actually just 8 * 330 Ohm's resistors in a neat package. And so, if you should have a resistor, you can just insert it instead in slot numbered “0”, as this is the only one we will use, when we only use one servo.

---end quote---

 So: rip out the darlington, insert a single 330 ohm resistor or buy a block of 330ohm resistors and use that. It doesn't have to be yellow...



oh... thanx. block of 330ohm resistors. I must read more slow. now I have to set only the srf05, for now doesn't work.

i can't get it to work even with my resistor on (same thing happens: it turns a bit when i first connect it but then does nothing).

i've tried to test my resistor with the multimeter (in continuity mode) and i saw it displays "0" whereas with my 220ohm resistor it displayed 218 or similar values.

 i guess my resistor's gone. oh by the way i once got the servo connected without anything...does that harm the servo?

I think I have the same problem. I bought a pack of resistor from The Source and it said on the package that its 20 in total and it said that there are five of each different resistor in there. (5)230, 330, 440 etc. but when I ask the guy at the store he said that each resistor can work for all of the resistor listed. but I guess he's wrong? maybe this is my problem with the servo. I read the manual and could not figure out whats wrong with it. I hot everthing working. it can run and the sensor works great. just need the servo to work.



the 330ohm resistor should have orange-orange-brown stripes on it follwoed by a gold stripe.  any other markings means that the resistor is not 330ohms!


Also make sure that you ALWAYS check the resitance of the resistor when it is DISCONNECTED from the board.  DO NOT CHECK RESITANCES WHILE IT IS CONNECTED!

Also, if you want to check resistance values do not usethe continuity setting on the multimeter...it has a resistance setting for a reason!.


If you want to test whether the servo is working use the following code:



     servo 0, 75

     servo 0,200

     goto main



the servo should go one way and then the other and repeat indefinitely...


point is that the stripes on my resistor are unreadable else i'd have already done that...and i just used the continuity setting because it seemed to work correctly with my other resistor...anyways i'll have to buy a better resistor! (with readable stripes this time!! :D i erroneously didn't check em when i bought it)

what do you mean by 'the stripes are unreadable'?  are they worn off?  can you post a pic?


have you tried measuring the impedance using the resistance setting on the multimeter?

my servo is moving both left and right but it move like left 3 second and right 3 seconds. My resistor is red,red, brown and gold I guess I got the wrong resistor.
thats a 220ohm you usually use a 330ohm resistor
no wonder I my servo go wacko because the resistor is not right. Thanks!