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Frequency Shift Register
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Frequency Shift Register
andrewF
Have been toying with this circuit for a couple of months. The basic idea seems to work although don't expect this to be useful for 'Switched on Bach' covers when granny visits.

I would appreciate any suggestions/comments/mods.

Still not sure about the signal input circuit, may need to adjust the resistors on pins 11 & 12 of the 4046 which set the operating frequency range of each chip. Maybe pots or trimpots here?

from my homepage -

The Analog Shift Register is well known, where voltages are shifted over three stages. This is the same in concept except it shifts frequencies and uses 4046 PLLs to do it.
Which means you have to be very optimistic to expect to see the frequency you fed into stage 1 to appear at stage 4.
For a single audio input and a clock signal, it produces 16 audio (or possibly CV/gate/trigger) outputs of related frequencies.

March 2010: Here is an UNTESTED draft of the full schematic. The circuit has been breadboarded with two 4046 stages and certainly put on a performance.
The clock ticks over the 4017 decade counter which enables the 4046 PLLs to shift their frequencies to the next stage.
first clock shifts PLL3 to PLL4, 2nd is PLL2 to PLL3, 3rd is PLL1 to PLL2 and 4th allows a new frequency to be introduced to PLL1.
Or you can feedback one of the outputs from PLL4 and get a loop going....oh yes:-)
But don't expect any kind of perfect tracking, these are 4046s. Your loops will drift horribly at best or just generally misbehave.
The frequencies are shifted by connecting the comparator outputs to pin 9 of the 4046s. The 4017 counter allows each 4066 switch to close in turn. The frequency from the comparator is smoothed to a voltage by the 10k resistor and 0.1u cap.
Once the 4066 switch opens, the voltage in the cap is held thanks to the hi-Z input on pin 9.
This voltage on pin 9 determines the frequency of that PLL's VCO.


schematic vers2 [72kb] pdf

MP3 demo

edit 18/3/10 updated link to vers2 of schematic
neandrewthal
Very exciting screaming goo yo
falafelbiels
interesting indeed, but I'm not going to try and break my brain over this one again I think. I don't understand PLL anyway. But I did get some extra 4046 in the mail when I ordered for the CGS digital noise. In fact I have all the parts needed I believe...
andrewF
Don't worry - PLL functions and behaviour are often the source of much animated discussion on electronics forums.

Generally for synths, they are good for noise/cacophony, as in the CGS digital noise or wogglebug.

this module won't be much different w00t
DGTom
neandrewthal wrote:
Very exciting screaming goo yo
falafelbiels
andrewF wrote:
Don't worry - PLL functions and behaviour are often the source of much animated discussion on electronics forums.

Generally for synths, they are good for noise/cacophony, as in the CGS digital noise or wogglebug.

this module won't be much different w00t


Well I kind of get the workings, just not the magic.
PLL = the new vactrol maybe? both being seemingly magical...
wetterberg
DGTom wrote:
neandrewthal wrote:
Very exciting screaming goo yo

PLLs AND shift registers in one thing? Sign me up, buddy!
BugBrand
Tuneful demo!

Sounds like a very fun concept!
DGTom
I was just looking at a partly disassembled lunetta PLL module... & remembered I'd used Pin 1 (SD or whatever the datasheet calls it) as a neat little indicator. I think the pin goes high when the VCO frequency locks to the incoming signal... or something like hmmm.....

Not sure how much use it would be here, but, may provide some sort of visual feedback?
andrewF
okay will give it a try
might make an interesting display

F.Mims had some FSK circuits with pin1 NORed to pin2, will try and find them.
DGTom
I'm pretty sure Doepfer uses pin 1 in some way for the LED on the A-196 as well... or at least the way the 196 blinks at me is very similar to the way my lunetta PLL does the same.

My module was just straight from the TI datasheet with pretty similar values as you have for the cap / resistor inbetween VCO out / VCO in.

With 4 of em all going & some LEDs for the 4017 outs that'd be some tasty blinken It's peanut butter jelly time!
andrewF
don't suppose you could have a look at the Offset pot and range switch of the A-196?
I'm guessing it is 1M and the switch will select different caps.
After reading Scott R. Gravenhorst's PLL article maybe a max freq pot for each stage would be interesting......so would range switches and LPF damping pots, but maybe the feature bloat would be a bit much

cheers
neandrewthal
The offset pot is C50k.

Range switch has 3 caps attached. From small to large marked:

.1
10n
105
andrewF
Thanks
looks like this circuit will need some refinement to work out the best functions to bring to the panel.

which of these controls and the frq pot are used most often?
DGTom
damn, thought I replied... autumn heat must be getting to me confused

I'd say the range switch would be usefull in addition to the pot, altho, with a 1M pot you can get quite a range out of the 4046.

A pot would be cool for the LPF, but, that could be a switch as well, Fast / Slow or Tight / Slewy grin

The other thing I was thinking, instead of having so many outputs, maybe multiplexing those? a pair of 4052s & you could have 4 outs or maybe 2 4051s... still, it'd need another counter (or 2) then I guess hmmm.....
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