[sdiy] 4017 sequencer

[harrybissell]

My guesses...

1:  you only have 5V to work with... so that would be 5 octaves in a perfect

world.  1K is pretty low and you are going to lose some voltage.

2: If you don't have a summing amplifier (opamp) following those pots
they'll
interact... because ONE of them is held hign... but the other 7 (or 9
however many
you got) are low.  You need to isolate them.  A crude but simple way is to
add a
diode to the wiper of each pot (anode to the wiper..) then tie all the diode
cathodes
together. This will form a simple analog 'or' gate where the highest voltage
(the step that
is ON) will get output. Downside is that the lowest .7V of the range of each
pot will
get wasted... and you'll lose the same .7V at the top.

A lot of folk use analog multiplexers like the CD4051... so only one pot is
active at a time.

let me know if any of this fits your case. I can try harder if not...

H^) harry

daryl groetsch wrote:

> I'm working on a 4017 sequencer (actually a 74HCT4017N, all i could find
> locally). It's very basic, clocked by a 555 and each number output 0-9
> has a 1K pot on it, then to a CV jack. I'm running it on a +5V computer
> power supply. My problem is when I change the pitch of a step, the pitch
> of others are affected. All pots and jack are grounded, and I've tried
> various VCOs.
>
> Also, even with bigger pots the pitch range is about 1 octave. How  can
> this be increased?
>
> Thanks much in advance!
> Daryl
>
> http://www.synthnoise.com