It's B, and fairly common in electronics and easy to do. let me explain.
Both the Cliff and the new type jacks I use have two sets of contacts - Normally Open (NO) and Normally Closed (NC). This means there's a
mechanical contact made to the NC contact in it's resting position
(nothing connected) that's broken when a jack is inserted and then
re-directed (physically) to the NO contact.
I've hardwired an 8 volt DC voltage to the NC contacts of the two
input jacks, which means when nothing's connected to those inputs that
DC voltage is fed into the attenuator so those two knobs determine how
much of that voltage passes out, with the 8 volts being the maximum.
When an external signal is inserted into the jack however this
'normaled' connection is broken and the attenuator now gates the
amount of that external signal is passed to the output.
hope this helps,
- P
--- In PLAN_B_analog_blog@yahoogroups.com, "monroeeskew"
<monroe.eskew@...> wrote:
>
> I'm a little confused about the elf leveler module. The description
says it will output a fixed
> voltage when no input is present. Does this mean--
>
> a) The knob is simply determines how much V is added to the incoming
V at any time.
>
> b) There is a switch that detects whether something is plugged into
the input socket. If yes,
> it attenuates any signal. If no, it outputs a fixed V depending on
the knob position.
>
> c) If a nonzero signal is present, it is an attenuator. If zero V
comes in, it outputs a fixed V.
>
> Now, (a) could be of limited use, (b) would be great but seems
doubtful, and (c) might make
> for some neat effects but would generally not serve the purposes of
audio and CV
> processing.
>
> Or is the answer: (d) The description is a typo; it is just an
attenuator?
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