Go Down

Topic: replace digital potentiometer in 9v - 12v circuits (Read 3688 times) previous topic - next topic

Othersounds

Sep 01, 2011, 12:00 pm Last Edit: Sep 01, 2011, 01:26 pm by Othersounds Reason: 1
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

Felix Luque Sanchez
http://www.othersounds.net

Edsoncan

You can use CMOS switches and fixed resistance, is not very accurate but it is simpler and more flexible

Othersounds

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
Felix Luque Sanchez
http://www.othersounds.net


Grumpy_Mike

@Edsoncan - if he connects that to a 12 volt circuit he will blow up his arduino. That is only good for 5V circuits.

Othersounds

#5
Sep 02, 2011, 10:57 am Last Edit: Sep 02, 2011, 03:20 pm by Othersounds Reason: 1
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
Felix Luque Sanchez
http://www.othersounds.net

Grumpy_Mike

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

Othersounds

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
Felix Luque Sanchez
http://www.othersounds.net


Go Up