[sdiy] Tuneable CV Quantizer

[Theo]

Yes sure, but in that case you have a 3 or 4 bit AD  made out of the 3914
and a priority decoder.
A way more complex and expensive solution than a 1 comparator per bit flash
converter.

A other option is to use the 3914 in BAR mode and have every output control
one 4053 switch element.
You can then chain the switches so that the pot connected to the "highest"
active switch goes to the output.
(infact a priority decoder made from cmos switches)
But for BAR mode a row of opamps is more cost-effective than the 3914.

Theo


From: Chris Crosskey <chris.crosskey at vicon.com>

> Yo ucould still use the 3914 etc if you strapped a priority encoder on it
>
> > -----Original Message-----
> > From: Theo [mailto:t.hogers at home.nl]
> > Sent: 27 September 2001 17:26
> > To: Curtin, Steven D (Steven); synth-diy at dropmix.xs4all.nl; 'John L
> > Marshall'
> > Subject: Re: [sdiy] Tuneable CV Quantizer
> >
> >
> > The most common "VU" meter ICs are the LM3914, 15, 16.
> > These can be cascaded, so more than 10 steps are possible.
> > The LM3914 is not UV but linear and might be the best choice
> > for use as a
> > quantizer.
> >
> > However all these IC have a drawback.
> > At first sight DOT mode suggest that only one output at the
> > time is active,
> > however this is not true.
> > The "levels" overlap for a few mV, so when changing from one
> > level to the
> > next two outputs are active.
> > This limits the usability as a quantizer, because when your
> > input voltage
> > hits one of the "in-between" voltages the output is the sum of the two
> > levels.
> > Especially with slow changing inputs, this may cause unwanted effects.
> >
> > I tried to overcome this by using a feed back method, so when the next
> > output gets active it pulls the input voltage up.
> > This works, but I still got short peaks in the output.
> >
> > An alternate option is to use a simple 3 or 4 bit AD build from 4
> > comparators (opams, logic gates, whatever) and a multiplexer.
> >
> > Theo
> >
> >
> > From: Curtin, Steven D (Steven) <sdcurtin at agere.com>
> >
> > > Another thing that would work is the VU meter chip (don't
> > remember the
> > > number) with the LED outputs- you then run each output
> > through a pot and
> > sum
> > > them together.  This has been mentioned in this forum many
> > times as a good
> > > tunable quantizer/sequencer.  You're limited to 10 steps, however.
> > >
> >
> >
>
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