[simpits-tech] Momentary on-off

[Jim Sturcbecher]

Will try and find some time within the next week to do that for you all.
Will see if I can also calculate the R and C values for you too. This is
just a simple standard circuit out of my head. Used a lot. Can be
greatly improved if switch happens to be a SPDT momentary toggle.

Later,

Jim.

At 8-10-03 22:03, you wrote:
>*boggle*
>
>Hey Jim, could you draw up a schematic of this and upload it to the
>website?  Us slower types could use the help. :)
>
>Great post!
>
>g.
>
>
>On Wed, 8 Oct 2003, Jim Sturcbecher wrote:
>
> > Recipe as follows:
> >
> > 1 - Connect one side of the switch to ground.
> >
> > 2 -  Add a pullup resistor to VCC on the other switch contact. this
> >       gives you a normally high output that goes to ground when the
> >       button is pushed.
> >
> > 3 - Feed this signal via a RC network (series resistor, then cap to gnd)
> >      to lose the switch-bounce noise.
> >
> > 4 - This then goes into a 74LS14 Schmitt trigger invertor.
> >
> > 5 - You will now have a nice clean high-going signal out of the invertor
> >      when you push the button.
> >
> > 6 - Feed this to the clock input of a D-Type flip-flop (74LS74) which has
> >      the /Q output connected back to the D input and both /SET and /CLR
> >      connected to VCC.
> >
> > 7 - Now every time you press the button, the Q output of the flip-flop
> > will
> >      change state.
> >
> > Voila, one change-over switch from a single push-button. You can drive
> > the leds from the Q output through a transistor to take the current.
> >
> > Serve and enjoy.
> >
> > Jim.
> >
> > At 8-10-03 18:57, you wrote:
> >       Quick question:
> >
> >       I need to make a momentary pushbutton switch turn some LEDs
> >       on and off. I.E. you push the button once, they turn on, you
> >       push it again, they turn off. Any ideas?
> >
> >       Brian
> >
> >       PS - I've been having trouble lately with my messages coming
> >       back from simpits-tech as undeliverable my first try. Anyone
> >       else having this?
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>
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