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 Forum index » DIY Hardware and Software » MusicFromOuterSpace.com designs by Ray Wilson
16 step seq voltage source question
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ashleym



Joined: Aug 20, 2009
Posts: 181
Location: uk

PostPosted: Fri Feb 17, 2012 2:14 pm    Post subject: 16 step seq voltage source question Reply with quote  Mark this post and the followings unread

Evening All,

I am building Ray's 16 step sequencer and I am not sure about one feature I want to add.

Currently the voltage source via VS1 gives about 7.5 volts. I want to make this switchable to something like 2.5/5/7.5V (or H/M/L according to my non-comittal front panel legend). I know I need to look at the circuitry around VS1 but I want sure on the best place to put a switch with some resistors. Do I switch the feedback and input resistors R25 & R26 (or perhaps only one of these to change the feedback/input resistor ratio- I was thinking to change both to keep the values working well in the circuit).

OR

Do I switch the values of the resistors going in to the non-inverting input of U1A, ie R1, R2 or R3?

BTW here is the panel I am working to. The circular Thomas White layout doesnt appeal to me when all my other panels are on a grid. But I have half inched some of his graphics. No there arent any fine tune pots for regular CVs the range control should help and for pitch CVs I have integrated (there is too much scope for punning here Laughing ) Ray's quantiser so I dont need to fine tune. No there arent any step LEDs either. Well actually there are, they are integrated in the gate switches. Each switch contains a separately controlled LED ie not one that works like a power on indicator.

Here is a picture from iPhone, I might put a better one up with flashing LEDs when RS deliver the other 8 switches.........


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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Fri Feb 17, 2012 7:51 pm    Post subject: Reply with quote  Mark this post and the followings unread

I may be wrong, but I think you could just change R25 from 200K, 100K and 47K.

That stage uses a 2.5V reference, and then multiplies it by 4 to get 10V. If you change the feedback resistor it will change the multiplication factor.

That's a great looking panel - very retro mad scientist look to it.

Gary
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ashleym



Joined: Aug 20, 2009
Posts: 181
Location: uk

PostPosted: Sat Feb 18, 2012 5:29 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for the advice and comments on the design. I think your option could be the best. I might attach some flying leads and test. As for the design, this is what is so great about SDIY- a chance to express yourself electronically, musically and aesthetically. One, none or all of these.
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