Odp: [sdiy] inversion, CMOS, etc.

[Ken Stone]

It really sounds like you want something like the Peak and Trough by Serge.
Have a look at my "Analogic" which does a similar thing.

http://otherunicorn.0catch.com/synth/ under "modules"

Ken

>----------
>>From: "Roman" <modular at go2.pl>
>>To: "gavin" <elmystico at earthlink.net>, "synth" <synth-diy at dropmix.xs4all.nl>
>>Subject: Odp: [sdiy] inversion, CMOS, etc.
>>Date: Fri, Aug 2, 2002, 5:33 PM
>>
>
>>OTOH you say to
>>leave the wave
>>itact and cut the lower peeks, so you simply need
>>a resistor and a diode
>>to ground.
>
>Pardon my possible ignorance here, as I understand it I would actually need
>a diode in series and a small resistor to ground to make a small half-wave
>rectifier, so that the positive peak would pass through the diode and the
>negative peak would be blocked by the diode and bled off through the
>resistor to GND.  Maybe that's not how it works and if so I'd like to know
>how it does work because then I'm operating on wrong info about how diodes
>work.
>This is what I imagine the half wave rectifier to look like.
>
>     +5V/-5V   ---|---D|------   +5V/0V
>                  |           
>                  R
>                  |
>                 GND
>
>  
>What I'd like to do is combine the HW rectifier with the passive summer to
>create a pot crontolled sort of "sunrise" effect of the wave going up and
>down the "horizon" of the ground line (sorry for the "metaphysical imagery,
>I knew my interest in analog synthesis and those high school LSD experiments
>had something to do with each other...)
>
>Something like this:
>
>/\__/\__/\__/\__/\   pot turned all the way down, +5V peak
>
>
>/\  /\  /\  /\  /\
>__\/__\/__\/__\/__\  pot turned all the way up, +10V
>
>i'd like to make this function voltage controllable also, by adding another
>summer between the signal and the input from an LFO or other LF voltage
>source.  The thing I'm wondering about is if for ultra high frequencies (RF
>type) do I need a special high speed diode for the rectifier or will a
>1N4148 type do the job?
>
_______________________________________________________________________
Ken Stone   sasami at hotkey.net.au  
Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>