[Swansea Hackspace] Project

[Aled]

You could even do this without a micro controller, a simple circuit using a 555 timer chip would work to control the relay and cost only a few pennies.

Here is an example of a circuit to control a relay-

http://www.555-timer-circuits.com/servo-tester.html

You could then use a rotary knob to control the position of the claw, or modify the circuit for open and closed positions with 2 buttons and a capacitor.

Aled.

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On Wed, 9/3/16, Justin Mitchell <justin at discordia.org.uk> wrote:

 Subject: Re: [Swansea Hackspace] Project
 To: hackspace at swansea.hackspace.org.uk
 Cc: "ody thomas" <jthomasdesign at outlook.com>
 Date: Wednesday, 9 March, 2016, 9:50
 
 On Tue, 2016-03-08 at
 23:41 +0000, jody thomas wrote:
 > Hello I
 was wondering if you could help, I'm designing a
 product. It's
 > going to be like the
 grabbers elderly use but motorised. Similar to
 > robotic arms used in manufacturing. I need
 to know how to move the
 > claw, i have
 looked online and have seen alot of servos being used but
 > I need to be able to control it using
 buttons and run of batteries. 
 > Thank
 you for any help 
 
 A simple
 enough project in principle, there are lots of
 grabber/claw
 designs on thingiverse that you
 can download and 3D print or laser cut. 
 
 They tend to use a single servo as the motor,
 you then need a very small
 amount of
 computer power to run the servo, one of the small Arduino
 family boards will do the job, even just an
 8-pin ATtiny85 chip will be
 enough.
 
 One IO pin to the servo, one
 or two for buttons, and the battery.  You
 can either have two buttons: one open, one
 close.  or have a single
 button that whilst
 held makes it close slowly, and when let go makes it
 open slowly.
 
 how strong the grip is will depend on a mix of
 the design of the claw,
 and what
 size/strength of servo motor is used.
  
 hope that helps
 
 
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