[sdiy] Tuneable CV Quantizer

[Chris Crosskey]

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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