LDR ideas

[Greg Joseph]

Well steve your idea is great and i hope you could develop ( i can't cos 
i'm just a beginner u know!!) but it sounds greaat if one could make 
something useable on stage, i'd just go mad for it!!!!
have good work!!

regards,

[greg]


steve.ridley at bbc.co.uk wrote:
> 
> The LDR-based "mini-theremin" project discussed recently got
> me thinking of other creative uses of LDRs, especially as
> Maplin will sell 100 LDRs for œ14 plus TAX.  These are just
> a few ideas "off the top of my head", so not yet tried.
> 
> 1.   A light controlled filter - several cascaded RC filters
>      using LDRs for the resistors, with overall feedback
>      via another LDR.  A dual op-amp and a handful of passive
>      components should complete it.  Buffering each stage
>      should improve the performance.   Move your hand between
>      the LDRs and the light source to vary the frequency and
>      resonance.  Angling your hand will cover some LDRs more
>      than others may alter the slope.  Switchable filters to
>      adjust the range.
> 
> 2.   Light controlled all-pass filters - similar to above.
>      Set it up as a phaser.  Hold it out of the window.
>      Cloud-controlled phasing!!!
> 
> 3.   Light-controlled mixing.  Taken to an extreme, it may
>      offer a solution to the Synthi A matrix problem.  Make
>      a matric of LDRs, cover over the ones you want to
>      attenuate.  Punch holes in a piece of thick card to
>      make presets...
> 
> There are also possibilities of LDR based touch keyboards etc
> too, but I'm sure someone must have tried some of these ideas
> before.  I know of ancient tone generators based on LDRs and
> spinning glass disks with patterns painted on - went noisy due
> to dust, insects etc.  Daphne Oram did similar things with film.
> 
> There are a few serious problems with all of these, and the
> worst one will be the light source.  Under artificial AC lighting,
> there will be 50/60Hz modulation, especially with flourescent
> lights.  Under stage lighting conditions things will fairly wild!
> 
> Any comments?
> 
> STEVE RIDLEY


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