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Analog shift register questions & opservations

2003-11-19 by Larry Hendry

Well, I finally wired up my two ASR modules behind a single MOTM
style Stooge panel. My PCBs have been done for weeks but I have been
waiting for my new Stooge jack only brackets to mount everything up
and wire it.

My impression is that the circuit is working fine, but that I need to
make some changes. I installed 47n caps for Cx per the part list and
used the "box style" metal films per someone's Mouser parts list.

I don't seem to be getting the desired results with these. I think I
am getting some droop when the clock frequenmcy is slow-ish, which
results in a rising CV out (per description). I have VCOs attached
and can detect the voltage change with a rising frequency.

So, I am wondering what parts others have used. According to the
instructions, I should be using a low leakage cap. These may not
quality. So, I am thinking I will change all my Cx out to 100n to
200n range and use polypropylene. Any experience anyone has to offer
will be appreciated.

Next, my initial observation is that a negative voltage at the input
is not going to work at all. Any others care to comment?

My next question conerns the imput impedance. Is there any specific
reason for the 22K input to TL074d? Does it not make any sense to
raise the value of the two 22Ks and apply the same percentage
increase to the 10K feedback resistor to have a higher input
impedance load on sensitive voltages like 1v/oct control? I dunno.
That's why I ask.

And, finally, I am thinking about other ways to use this module.
What if a gate signal was used at the input. Could one use the ASR
for a evenly distributed gate delay?

And, how about a method for controling phase relationship between
synched oscillators? If each outputs were patched to the sync inputs
of three slave oscillators. The sync master oscillator pulse would
go to the ASR input, and the frequency applied at the ASR clock in
could cause the oscillators to sync at varying degrees of phase
shift.
I'm off to try this. :)

Anyhow, I'd love to hear from other ASR users about their experience
with these issues and anything else they would care to discuss about
this interesting circuit.

Larry Hendry


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