[sdiy] interlocking switches

[Roy J. Tellason]

On Sunday 14 August 2005 07:12 pm, you wrote:
> No pic solution from my side. (But you already guessed that.)
> http://www.oldcrows.net/~jhaible/polykorg/jh_3200_digital_1.gif
> The drawing contains two such selectors, so you only need half of the
> circuit.
> Two 4000 series ICs for 8 channels.
>
> JH.

Not bad.  Though I like somebody else's suggestion of using a '373 latch, 
which doesn't have to go to the BCD side of things at all.  I can use the bit 
of the circuit you point to for clocking the thing,  or some variation on it.  
Just one transistor,  and a couple of other parts...

> ----- Original Message -----
> From: "Roy J. Tellason" <rtellason at blazenet.net>
> To: "SDIY list" <synth-diy at dropmix.xs4all.nl>
> Sent: Sunday, August 14, 2005 9:19 PM
> Subject: [sdiy] interlocking switches
>
> > I *know* I've seen this in some service manual or other,  but can't
> > remember where...
> >
> > Say you have a row of buttons,  and you push one,  an LED lights up. 
> > When you push another,  that light comes on and the first one goes out. 
> > Sort of like the old mechanically-interlocked switches I remember from
> > ages ago.
> >
> > Posted about this elsewhere,  and have of course the immediate suggestion
> > to throw a processor at it,  which I'm not inclined to do,  and some more
> > that discuss using lots of logic.
> >
> > Can any of you guys point me toward a circuit like this?  I know there
> > were a fair number of commercial keyboards out there that used such stuff, 
> > rows of momentary-contact switches with LEDs and some toggled on/off, 
> > while others "interlocked" like I'm talking about here...