RE: how Beefy? Large Servo [TANKS]

["Doug Conn" <dwconn404-at-comcast.net>]

Title: Message

Wow ! Your suspension and steering look great ! I’m SO sick of people who actually know how to fabricate things correctly. My work looks like its built using bear skins and flint tools.

 

This is an intriguing design because I already have the wiper motor and regulators sitting around my shop searching for a purpose. It’s interesting how the ‘smart bear’ used the servo positioning to drive the gear motor though the H-bridge board. I guess that’s functionally equivalent to the feedback pot in the servo kit that Steve pointed out. For my vehicle, however, there’s just no room to mount a big gear motor for steering.

 

Another thing I ran into with those wiper motors was coupling anything to its output shaft. Mine have a tapered spline portion of the shaft and then a short threaded portion. Are yours that way ? How did you connect to the shaft ?

 

Thanks,

Doug

 

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From: tanks-admin-at-rctankcombat.com [mailto:tanks-admin-at-rctankcombat.com] On Behalf Of Steve Butzen
Sent: Tuesday, March 06, 2007 3:33 PM
To: tanks-at-rctankcombat.com
Subject: how Beefy? Large Servo [TANKS]

 

 

Re:Make a extra strong servo

 

  Here’s what I did on my staghound project.

 

 

Notice:servo in lower center of above picture.  (Ignore the plastic spash guards that have 100% vitamin c)

 

 

could that be a 1:6 scale M1A2 Abrams in the background…..naaah couldn’t be)

 

 

 

Here’s what you need:

 

 

 

3 Capacitors   .1uf  $1.99 at Radio Shack

 

 

Windshield wiper motor     ebay  $12.95 +shipping/handling  of  $17.96 (buy several and save some money on shipping)

 

http://cgi.ebay.com/2000-2001-Saturn-L-Series-Wiper-Motor-NEW-Wholesale_W0QQitemZ160092769450QQihZ006QQcategoryZ2594QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

 

 

High Power H-Bridge DC Motor Driver Board

 

Tecel d200                                        $35.00  +  $4.00 shipping

 

http://www.tecel.com/d200

 

(the two wires from your modified servo go to the “IN1 and IN2” lines,+5 volts from the LM7805 go to the EN and 5V lines.  Battery plus/minus and Motor lines as marked)

 

 

 

5 Volt voltage Regulator

  LM7805   appox: $6.00 order from Tecel no additional freight

 

 LM7805

This is a 5 volt voltage regulator; use it to power the d200 as well as your RC receiver

 

 

 

Futaba S3003 Servo             $10.99 From Tower Hobbies or Ebay  (or get one out of that box of RC stuff left over from the last airplane you crashed, that’s where I got mine!)

 

 

Then: respectfully copy what this “Smarter than the average bear” did.

 

http://www.fieroaddiction.com/servo.html

 

Basically the receiver send the signal to the servo, the servo decodes it and passes along the pwm signal that normally goes to the servo motor to an amplifier that provides the power to drive a bigger motor, and then by a linkage back to the servo position feedback keeps the motor where you want it.

       The set up works just like a servo, move the stick a little the motor turns a little and stays there, deflect it more, the motor turns farther and stays there.  Release the stick and the motor return to its original position.  So for your $89.00 bucks you get a Really powerful servo. (less than $89.00 if you already have an s3003 servo and a small dc motor.

 

       Note: this set up without the connection back to the servo provides proportional directional control useful for perhaps a turret spin control.  Ie: Deflect the stick slightly to the right, the turret will turn slowly right.  Deflect the stick fully right and the turret will spin faster right. Release the stick and the motor/turret stops (same for left spin).

 

I want to echo the fact these large motors are quite powerful and possibly dangerous so unless you are an American Counter Terrorist Agent and need to get some information from some evil Russian ambassador,  KEEP YOUR FINGERS OUT OF ROTATIONAL PATH!

 

 

 

Steve “Superman wears Jack Bauer pajamas” B.