Society of Robots - Robot Forum

General Misc => Misc => Topic started by: Ledhed66 on November 30, 2008, 10:35:45 PM

Title: Hitec servo question
Post by: Ledhed66 on November 30, 2008, 10:35:45 PM
First of all thankyou for this forum.  My 8 year old son has been after me for a year and a half to build a robot with him.  I don't know how I have missed this for so long.  I am wanting to build the 50$ robot.  I have 4 hitec servos from a r/c plane project that crashed and burned 20 years ago.  The servos have the # hs-500cw on them.  I am unable to find any information to compare them to the hs-311 servos listed in the parts list.  Thankyou in advance for any help!
Title: Re: Hitec servo question
Post by: Trumpkin on December 01, 2008, 09:12:58 PM
So... what exactly is the question?
Title: Re: Hitec servo question
Post by: Ledhed66 on December 01, 2008, 09:54:33 PM
Will these servos work in place of the hs-311
Title: Re: Hitec servo question
Post by: HDL_CinC_Dragon on December 01, 2008, 10:19:42 PM
There doesnt seem to be any information on this servo anywhere on the internet... That sends up some red flags there. As long as the servos have the 3 wires hooked up to the right connector AND in the proper order, I dont see why not...
Title: Re: Hitec servo question
Post by: Webbot on December 02, 2008, 12:10:23 AM
Depends on how much 'you want to do it'. You've got 4 ancient (apologies!) servos that may or may not work.  The $50 Robot requires two servos - and HS311s are pretty cheap. Given you are a 'dad' then your budget is not quite as constrained as some junior members.

So buy yourself some new HiTechs for Xmas (cheaper than a turkey) and spoil your kid over the Xmas break.

You obviously aren't good at flying as your model crashed and burned  ;) but you don't say what electronics experience you have. Can you solder , do you have an iron? etc. If not - then your wife may need to buy you some other Xmas presents from the hardware store (or Digikey etc)
 

If this is your first electronic project then please refer to my posting at http://www.societyofrobots.com/member_tutorials/node/190 (http://www.societyofrobots.com/member_tutorials/node/190). Although this focuses on building a different $50 board it gives some general tips as to the sequence to add stuff to your board, and how to check as you go, so as to minimise problems at the end.

Title: Re: Hitec servo question
Post by: want2learn on December 02, 2008, 04:49:00 AM
There's only really one way to know: TRY.
Just because they're old doesn't mean they're useless (as long as they were'nt damaged in the crash).

Don't worry if the connectors are wired up differently, you can change the layout on the $50 robot board (if you're making it on veroboard/protoboard) or you can cut the connectors off and solder the wires to the board. There are many options here. This will be you're robot you can modify it to suit your needs (although it is a little easier to stick to whats known when it comes to fault diagnosis).
If you know what the wiring layout is already (or when you're testing to find out) I recommend stalling the motor and measuring the stall current; just to see if it'll be in the same ball park as the 311's.

If worst comes to worst then rip the board out, modify it for continous rotation and you have yourself 4 gearmotors all you need to do is freeform some H-bridges ,stick them in where the control boards used to be and take the control wires out alongside the power wires from the motor.
Just a few points to try and save you a few robot tokens for the one after this or to put towards some of the upgrades.
N.B. if you modify the servos with h-bridges you'll need to change the code for the robot, so may be best to leave them for the next robot project if you modify them
Title: Re: Hitec servo question
Post by: Admin on December 05, 2008, 09:45:49 PM
Wow I didn't know Hitec even existed back then! I wonder if Hitec would pay a shiny penny to buy them back from you? They should go in a museum ;D

For the less sentimental . . . there is no way of knowing they accept the now standard servo signals without trying . . . and I'm not sure how easily modifiable the servos will be. Basically open them up and see what's inside.
Title: Re: Hitec servo question
Post by: Ledhed66 on December 06, 2008, 10:54:43 AM
I went ahead and ordered the hs311 from Servo City.  They came in yesterday and had been upgraded to hs325hb for free.  I am going to try the old servos on my 50 robot and let my son use the new ones.  I'll let you know how they turn out after Christmas break. Thanks.