[sdiy] "scanner" or voltage-controlled routing?( vc stage-address)

Andreas Wetterberg andreas at wetterberg.dk
Mon May 4 21:00:09 CEST 2009


Very nicely explained, Dave! I think I will proto a setup using Tims 
idea of schmitt triggers first (since I have all those parts already) 
and I will hope that there won't be "dead spots" where none of the outs 
are active, if so, then maybe it's time to go for some 4066-switches or 
RS-flip flops, yadda yadda. Will keep you posted (although these 
projects usually take me years, not weeks ;) )

thanks all,
Andreas.

-- 

Dave Kendall skrev:
> Hi Andreas.
>
> One thing you might try, is to buffer your gate signal with a Opamp 
> wired as a voltage follower, or a transistor wired as an emitter 
> follower, and then wire the output of the follower to *all* the inputs 
> of something like a CD4066, or maybe 2 or more CD4066s if you need 
> more than 4 outputs.
>
> Wire the control inputs for each switch in the 4066 via a pull-down 
> resistor to ground, and then connect each control input to a switch 
> that has +v or GND on each lug of the switch. Of course this could be 
> done with logic via gate on/off inputs too. (which is  what the 
> pull-down resistors are for.) I have used a dual pole toggle switch 
> with a centre-off position for this sort of thing before. When the 
> switch is up it is ON, when it is down, the gate input socket is 
> disconnected from the control input, and the switch connects the 
> control input to GND so it is OFF, and in the centre position, the 
> pulldown resistor keeps it OFF until a positive gate into the CONTROL 
> IN socket switches it ON.
>
> If the gate signals you are switching and the control on/off switches 
> are at different levels, it gets more complicated, and you might need 
> over-voltage protection, and possibly comparators on the gate or 
> control inputs to increase the level.
>
> If it's all at +5V, it is easy. :-)
>
> Is that more like what you are after?
> Hope it helps.
>
> cheers,
> Dave
>
>
>
>
>
> On May 1, 2009, at 22:03, Andreas Wetterberg wrote:
>
>> Hi Dave, thanks for getting back to me!
>>
>> What I have in mind is the other way around: Routing a simple gate 
>> source to different destinations - this would have the benefit of 
>> allowing me to split it into as many "rows" as I'd like, etc.
>>
>> I hope that makes a bit more sense? The (very cool) example below 
>> shows 8 sources that can be switched to any of two outputs. I'd like 
>> one source that can be sent to any of x outputs - doesn't have to be 
>> a full-on VC switch as such, I just need to run +ve into different 
>> destinations.
>>
>> Andreas.
>>
>> Dave Kendall skrev:
>>> Hi Andreas.
>>>
>>> I may have misunderstood your aim, but have you seen this?
>>>
>>> http://hem.bredband.net/bersyn/VCO/2x8p%20VC%20switch.gif
>>>
>>> There's a very brief explanation of its use here....
>>>
>>> http://hem.bredband.net/bersyn/VCO/lfo.htm
>>>
>>> maybe this will help with some ideas?
>>>
>>>
>>>
>>> cheers,
>>> Dave
>>>
>>>
>>> On May 1, 2009, at 21:21, Andreas Wetterberg wrote:
>>>
>>>> hey all,
>>>>
>>>> okay, this idea has been a driving force in my modular explorations 
>>>> for a while now:
>>>>
>>>> I want to do a stage-addressable sequencing thing; 0-5v would 
>>>> switch it between stages, which would be x amount of voltage 
>>>> divider outputs, ala a normal sequencer.
>>>>
>>>> I know the Serge TKB, cgs Programmer, Wiard Sequantizer and, in 
>>>> part, the Blacet Scanner and Doepfer a-152 v.addressed switch all 
>>>> have this functionality, but I am considering whether there would 
>>>> be much simpler ways of doing this?
>>>>
>>>> At first my thoughts drifted towards the lm3914 Dot/Bar display 
>>>> driver for LEDs - simply set it to Dot mode and route each of these 
>>>> outputs through the attenuators and out. However I think it was mr. 
>>>> Haible who said that it had notable slew between its stages - the 
>>>> crossfade function also detailed in the datasheet for the lm3914.
>>>>
>>>> Now, would a simple ad-da process be useful to make a stair-case 
>>>> signal that would eliminate this slew?
>>>>
>>>> just throwing some ideas around here :)
>>>>
>>>> best,
>>>> Andreas.
>>>> _______________________________________________
>>>>
>
>




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