vc wave select

[Grant Richter]

Sorry about the cryptic post... let me clarify that.

The LM3914's have a relatively low input impedance. It is good to buffer
it.
Make a an inverting summer out of any op-amp. Lets say 100K resistors.
The reference for the LM3914 is adjusted to +10V using a 1K resistor and a
7.5K
resistor.

Use 10K resistors in place of the LED's on the LM3914 and wire 8 of the
taps into the eight inputs of a CD4532 priority encoder running on 15
volts.

The LM3914 outputs go low when activated. So, we add a 150K resistor from
the -15 volt supply to the summing node of the op-amp. Now the with the
control
input at 0 volts, the summing amp output is at 10 volts and all the LM3914
outputs
are low and the CD4532 outputs 000 binary.

As the control input goes from 0-10 volts, the summing amp output goes from
10v to 0v and the outputs go high in order. The CD4532 then outputs binary
code in order 000 to 111. You can cascade two such sections to get four
bits.

The design originally appeared in the quantizer module for the Sadin Image
Processor,
an analog video synthesizer. Using LM319 comparators instead of a LM3914,
the three
outputs of the CD4532 are fed to the RGB inputs of a RGB to NTSC encoder.