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Author Topic: replace digital potentiometer in 9v - 12v circuits  (Read 3342 times)
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Hi,
I want to control variable resistances (2-10-50-100K, 1MOhm) in circuits via my computer (replace a pot by a software control).
I have read about digital potentiometers but in my case I have circuits powered at 9v and 12v (and with double power 9v/-9v/0v …) …
There used to be digital potentiometers up to 15v in DIP (Dual Inline Package), but they seem discontinued…
I suppose there is a case-by-case solution without using digital pots: I have 2 chaos generators circuits (see attached images) where i need computer control over the potentiometers.
The one called chua is more simple, there is only one variable resistance to control (1.5 or 2k):

The one called Jerkster is more complex with several variable resistances (R14,R21,R24,R2,R22):

Any solutions for these examples? Any digital pot in DIP package with up to 12v operation available? Any examples with schematics are very welcome!
Thanks,
Felix



* chua.jpg (45.87 KB, 898x461 - viewed 78 times.)

* jerkster.jpg (128.22 KB, 1080x737 - viewed 73 times.)
« Last Edit: September 01, 2011, 06:26:17 am by Othersounds » Logged

Felix Luque Sanchez
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You can use CMOS switches and fixed resistance, is not very accurate but it is simpler and more flexible
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Hello Edsoncan,
Thanks for your quick input.
There seems to be a lot of types, could you please explain me more in detail witch kind of CMOS switches should I use and point me to some specific models?
And how should I connect it to my 0-5v Arduino to control the CMOS switches as a variable resistance?
A schematic will be of great help, if someone can make it …  
Thanks
F
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@Edsoncan - if he connects that to a 12 volt circuit he will blow up his arduino. That is only good for 5V circuits.
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Edsocan, thanks for the schematics!
Mike, thanks  for pointing that detail ;-)

I'm new to Multiplexers/Switches, and i don't get exactly how they work in this configuration... But are we using it as a voltage controlled resistance?
If it's the case, to work with the arduino and a make a 12v control signal, could we  use for example something like an uln2003 to feed the max4051 I/O pin?

arduino pwm output 5v--- uln2003 12v--- Max4051 I/O pin 3?

Thanks
F
« Last Edit: September 02, 2011, 08:20:29 am by Othersounds » Logged

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Just a crude switching in of resistors will only work if you are after a potential divider which in the case of some of your pots you are not.
Most digital pots are 5V
http://en.wikipedia.org/wiki/Digital_potentiometer
but this is the only one I know that will work up to +/- 16V
http://uk.farnell.com/analog-devices/ad5293bruz-20/ic-dig-pot-1024pos-20k-14tssop/dp/1827274
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Hi Mike,
Yes, In fact i was thinking of using this one:
http://www.analog.com/en/digital-to-analog-converters/digital-potentiometers/ad5290/products/product.html
with the arduino library:
http://www.arduino.cc/en/Tutorial/SPIDigitalPot
and the dip adapter:
http://www.epboard.com/eproducts/protoadapter.htm#TSSOPtoDIPAdapter

It will be an expensive solution ... but should work ...
F
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Yes that looks fine to me.
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