[sdiy] AR envelope and 4066 (now complete)

[Ken Stone]

Crude solution to your problem - parallel some gates, each with its own 1k
resistor. Each additional one will allow more current through, giving you a
quicker attack.

Ken

>hi,
>
>you were both right. I did realize it was pushing a huge current though. 
>Actually, I didn't check what the data sheet said until I blew the first 
>4066. I was a little confused (and still am) because some people seem to 
>have managed to short it to ground, or V+ without limiting. atleast that 
>is what thier schematics show. I also was thinking that the 'on' 
>resistance would help and that only short bursts of high current would 
>be ok. I still think the short bursts probably allow a larger current 
>but I don't know how to check something like that without destroying the 
>chips. For now, I put in 1K resistors and it hasn't burnt, or gotten 
>warm yet (12ma). My test was to set min attack and decay and run a VCO 
>through it to switch it quickly. I ran it for about 30 minutes so far. A 
>bit shorter attack time might be better but I think this is good enough 
>for me.
>
>an example of shorting switch is ray wilson's other retriggerable adsr 
>here: http://www.musicfromouterspace.com/analogsynth/adsr_new.html
>
>I'm also looking at my oakley ADSR which uses only 47ohm resistors. 
>There is a note in the user's manual that says with fairchild 4066s, the 
>resistor would be better at 330ohm. My 4066s just happens to be  a 
>fairchild.
>
>I have updated my webpage with a picture, and new schematic. it is here:
>http://www.sdiy.org/destrukto/modular/ar-ad_transient.html
>
>-ryan williams
>
>
>Simon Brouwer wrote:
>> Hi Ryan, Gabriel,
>> 
>> gabriel at lindeborg.org wrote:
>> 
>> 
>>>Hi Ryan!
>>>
>>>You do realise that you by closing the 4066 switch and setting the Attack
>>>to 0ohms will have a hefty current running thru the 4066 until the cap is
>>>fully charged? Sort of like shortening the 15V to ground...
>>>
>>>//Gabbe
>
>> 
>> According to the data sheet the maximum DC current into any pin is 10
>> mA, and the on resistance of a switch @15V is 125 ohms, so in your case
>> the peak current is 120 mA. I would add a 1k5 series resistor.
>> 
>> See: http://www.ee.washington.edu/stores/DataSheets/cd4000/cd4066.pdf
>
_______________________________________________________________________
Ken Stone   sasami at hotkey.net.au or sasami at cgs.synth.net
Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>