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In a message dated 12/3/05 7:49:37 PM, harrybissell@prodigy.net writes:<BR>
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<BLOCKQUOTE CITE STYLE="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px" TYPE="CITE"></FONT><FONT COLOR="#000000" FACE="Geneva" FAMILY="SANSSERIF" SIZE="2">Most of the Mesa/Boogie designs that use pairs of vactrols are doing<BR>
switching, not linear control. I haven't seen them do a real potentiometer<BR>
with a pair of vactrols. (I'd like to... and schematics or links ???)<BR>
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This is true. They often use one in series with the signal and another as a shunt to ground, with opposite polarity control signals for each. Presumably, this configuration enables them to completely attenuate the signal, with nothing bleeding past the two LDR's.<BR>
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It seems to me that it should be possible to rig two LDR's into three-terminal variable resistor configuration, but probably with rapidly diminishing returns in terms of cost effectiveness and performance. It sure would be nice to figure out a kind of universal (and cheap) voltage control circuit for filter resonance/feedback that doesn't eat up an OTA, though.<BR>
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