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[squidfanny]

I am wondering, if it is possible to use a 'light dependant resistor' to control the filter envelope on my MC-202 analogue synth..

Someone once mentioned that it has to be used with a transistor, so how does that work? Will it give me a similar control to the 'D-beam' controller which is on some modern synths, or is it a waste of time? :

Please excuse my ignorance if this is a stupid question, I am a noob still learning........

[Gordonjcp]

Work out how to add an external filter CV input.
http://www.kolumbus.fi/janne.husu/specs.html
Have a look at the schematic for the MC-202 analogue section on that site.  About in the middle near the bottom of the page, you'll see the CV mixer for the VCF cutoff CV, consisting of IC24b and all those resistors.  You're probably most interested in the way that VR11 and R192 form a variable potential divider between the positive supply and ground, and R217 mixes the resulting voltage in with the others.

If you want, I can post a more detailed explanation of how it works later this evening.

[squidfanny]

Thanks very much, I have the 202 open right now and I'm looking at the various components. I've been busy adding some of the mods from 'cykong's' website, but these mods were all pretty simple to do and there were photo's to see exactly what I was doing. I am a little nervous about poking around with the components as the unit cost me a fortune and I don't want to trash it.

If you could post any more information on the 202 then I would be really greatful and be your best friend.

So am I right in thinking that I basicaly need to add a CV input to the 'filter envelope' and then to use a LDR to control the CV? Is it simply a case of using an LDR instead of a pot, or are other componants required such as a transistor?

once again, please excuse my noobness..................:-)