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Electronics => Electronics => Topic started by: Trumpkin on November 29, 2007, 09:39:54 AM

Title: modifyng servos (again)
Post by: Trumpkin on November 29, 2007, 09:39:54 AM
I want to modify my servos now but I don't have the batterys for my microcontroller, can I just run it off of a couple of normal batterys?
Title: Re: modifyng servos (again)
Post by: cooldog on November 29, 2007, 11:19:08 AM
yes but i don't know how to connest them
Title: Re: modifyng servos (again)
Post by: Trumpkin on November 29, 2007, 11:34:01 AM
on the molex connector there are slits where the pins are showing I think I can just connect my batteries to that.
Title: Re: modifyng servos (again)
Post by: bukowski on November 29, 2007, 02:00:05 PM
Look in the $50 robot tutorial, it will have a description on how to power your robot with 4 AA's and a 9V instead of the battery pack. Basically, connect the 9v to your microcontroller power supply, and the positive of the AA pack to the positive servo wire, and use a common ground for all of them.
Title: Re: modifyng servos (again)
Post by: Trumpkin on November 29, 2007, 02:10:15 PM
I meant could I dirrectly power my servos for modifying them
Title: Re: modifyng servos (again)
Post by: Trumpkin on November 29, 2007, 02:12:27 PM
PS: bukowski, I meant Without the microcontroller at all.
Title: Re: modifyng servos (again)
Post by: bukowski on November 29, 2007, 03:19:17 PM
You could power the servo's with no microcontroller, but you need a way to send the correct pulse to get the servo to zero. That means either an rc transmitter and reciever or a microcontroller.
Title: Re: modifyng servos (again)
Post by: HDL_CinC_Dragon on November 29, 2007, 03:49:21 PM
You would need to create a circuit using a 555 timer to output the correct frequency that tells the servo to go to zero position. I think a 1400us is the standard for the zero position... Look at this page to learn about the 555. It even shows you a circuit diagram. Link (http://home.cogeco.ca/~rpaisley4/LM555.html)
Title: Re: modifyng servos (again)
Post by: Trumpkin on November 29, 2007, 03:50:49 PM
on the bottom of the main gear of my servos there's a slit that fits on the potentiometer shaft should I drill that out so that it can rotate freely from the potentiometer? (I'm guessing I should seeing as how your supposed to glue the potentiometer shaft in place.) thx
Title: Re: modifyng servos (again)
Post by: HDL_CinC_Dragon on November 29, 2007, 04:05:45 PM
Yes, you want to make sure that when the servo's internal gears are spinning, its not affecting the potentiometer at all. Be careful when doing this that you dont damage the gear.
Title: Re: modifyng servos (again)
Post by: bukowski on November 29, 2007, 04:15:24 PM
Ive only done this once, but...
You proboably dont need to drill it out. Often, this "slit" is a separate part from the gear.
On the servo's I modified, there was a bearing preventing me from popping it out, so I just clipped the pot head off instead.
There may also be a mechanical stop, look for a pin on metal gears or a plastic nub on plastic servos.
Read the tutorial on modifying servos!! It has basically all the info you need.
Title: Re: modifyng servos (again)
Post by: ed1380 on November 29, 2007, 04:36:49 PM
yes you can mod it.

take the pot out, and replace the pot with a resistor. 2.2k ohm IIRC

http://www.instructables.com/id/modify-the-hitec-hs-325-servo-for-continuous-rotat/