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DPRG: Re: Circuit Needed!

Subject: DPRG: Re: Circuit Needed!
From: Bryan Andersen bryan at visi.com
Date: Sat Nov 20 00:48:42 CST 1999

To get better switching characteristics one could use a DPDT 
relay, then have a SPST momentary switch energize the relay 
coil.  This will eliminate most of the in-between state 
problems.  There will still be a little switch bounce, but 
that can't be gotten rid of unless you go to solid-state type 
relays.  If you do decide to go solid state you can add in 
a debounce circuit to cleanup the state transition.


Brynn Rogers wrote:
> 
> ElectroDFW at cs.com wrote:
> >
> >     Hello All,
> >
> > I need a schematic of components that when a button is pushed, or a switch
> > depressed, by a mechanism, it will only allow the motor to go in the
> > direction other than which it is turning.  I know how to do a motor cutoff
> > switch, but I want it to only be able to reverse until the switch is no
> > longer pressed, and I don't know how to wire something that way... No
> > software solutions, please. I want this hardwired.
> 
> The simple solution (with a gotcha) is this:
> 
> a DPDT (double pole double throw) momentary contact push button will do
> what you asked,
> but it may not be what you want.
> 
>    _________________o 1      4 o
>    |                 \        /
>    |                  \      /
>    |                   \    /
>   / \                   \  /
>  | motor    - (Gnd)_o 2  \/  5 o____ + (Vcc)
>   \ /                    /\
>    |                    /  \
>    |                   /    \
>    |                  /      \
>    |                 /        \
>    _________________o 3      6 o
> 
> pins 1-6 are the DPDT switch, 2 and 5 are the common terminals
> 
> This will run the motor out to the limit switch, when it is hit, reverse
> it.
> then the switch will switch again and the motor will run the other way.
> 
> Of course unless you have something else controlling this the motor will
> oscillate around
> the opening and closing of the switch, possibly stopping with the switch
> in a half-way
> position that has no connections made.
> 
> a special type of switch called a make-before-break will short out your
> power source if used like this.
> (Those are rare)
> 
> Brynn
> --
> http://www.visi.com/~brynn to see my triplets !

- -- 
|  Bryan Andersen   |   bryan at visi.com   |   http://softail.visi.com   |
| Buzzwords are like annoying little flies that deserve to be swatted. |
|   -Bryan Andersen                                                    |

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