[sdiy] Muxes at maximum voltage.

[Ken Stone]

>> Im about to use a 4051 at +/- 7,5V and logic
>> to set mux channel driven from +6V, the specs
>> dont tell if 0 to +6V logic are enough for
>> logic (ViH) to drive the mux switch!
>> Anyone with this experience?

4051 has pins designed for this. P16 VCC +7.5
P8 VSS 0V/GND
P7 -7.5V
(excuse me for stating what you probably already know)

Your signal can then work between + and - 7.5 volts while the logic goes
between 0 and +7.5.  + 6 will be enough.

>If you really want to squeeze the 4051... locate it at the
>summing node of an inverting opamp. Put the input resistors
>on the other side. Run it on maybe +15 and run the ground at
>-.7V.  Voltage drop across the analog switches will be near
>zero... linearity is very good that way.
>
>H^) harry

For thses configs, try looking at the circuits on my page
-0.6V system as describe above by Harry
http://www.cgs.synth.net/modules/cgs28_seq_switch.html
http://www.cgs.synth.net/modules/cgs40_modulo_magic.html

A level shifting approach.
http://www.cgs.synth.net/modules/cgs34_asr.html

Ken
_______________________________________________________________________
Ken Stone   sasami at hotkey.net.au or ken at cgs.synth.net
Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
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