[REQ]Voltage controlled Potentiometer

[itp]

Dear All,

Digital potentiometer are available in the market. We can use these potentiometer to digitally control volume of a music system system. Anybody came across a Voltage controlled potentiometers. My purpose is to use it as a voltage controlled  resistance in an application.

Thanks and Regards
Itp

[Wizpic]

You can use it to control a voltage by placing one end to gnd and top pin to 5v (which is its max) and the you get voltage out on middle pin. When I tried this it worked but depends on how many steps you want, I prefer to 12-16 dacs to control voltage much better

[mars01]

I believe that the OP wants a resistor that can have the resistance adjusted by changing a voltage.

A quick google search found those:

- Page 16 from this datasheet: http://www.ti.com/lit/ds/symlink/lm13700.pdf
- http://www.aldinc.com/pdf/fet_11103.0.pdf
- and an app note from Maxim that show how to use a PIC controller and a I2C digital potentiometer to get what you want: https://www.maximintegrated.com/en/app-notes/index.mvp/id/4051

There are some devices (vactrols) that can work like a "resistor" with resitance adjusted by changing a voltage and they are quite linear. See here: http://www.qsl.net/wa1ion/vactrol/vactrol.pdf

[Crackn]

There are some devices (vactrols) that can work like a "resistor" with resitance adjusted by changing a voltage and they are quite linear. See here: http://www.qsl.net/wa1ion/vactrol/vactrol.pdf

newer vactrols (vactec) uses a combination of LED and LDR. older vactrols was a combination of incandescent light bulb and LDR... better linearity for audio applications like audio clipping protection on a power amp.

[metal]

which company makes them now, where do you buy these?

[PICker]

Have a look to this Application note from Arizona Microchip:
http://ww1.microchip.com/downloads/en/AppNotes/01316A.pdf
I do not kow if this could help you.

[Crackn]

More Information about Vactrols
http://denethor.wlu.ca/pc300/optoisolators/analogoptoisolatorintroduction.pdf



Posted on: 18 June 2016, 06:54:15 - Automerged

which company makes them now, where do you buy these?

last time I ordered from a local store. but you can find it online...
search for Vactrols, PerkinElmer, Excelitas Tech....

farnell UK has vactrols in stock.
http://uk.farnell.com/excelitas-tech/vtl5c1/optocoupler-single-channel/dp/1652517

[PICker]

DIY vactrol links:

https://www.muffwiggler.com/forum/viewtopic.php?p=796018
https://www.muffwiggler.com/forum/viewtopic.php?p=756093&sid=e3d6a61e48b46cdb1e72c11fc8b964eb
http://www.guitarpcb.com/PDF%20Files/DIY%20Vactrol.pdf
https://www.youtube.com/watch?v=Je5FS1A7Ys0
https://www.youtube.com/watch?v=eSBUkM1cGks
http://www.doepfer.de/a100_man/Vactrol.htm

I hope this could help you.

[bobcat1]

Hi

Once long time ago I use Jfet for current control working in conduct region(linear area of the Jfet) of the FET device, you can use voltage to control Jfet resistance
It works but in a very limited region.

All the best

Bobi

[titi]

Hi,
Opto FET can be also a solution, as it is opto insulated and the FET can be use as a variable resistor.
Here is an example :
http://www.edn.com/design/analog/4368893/Use-a-photoelectric-FET-optocoupler-as-a-linear-voltage-controlled-potentiometer
http://www.digikey.com/en/articles/techzone/2012/dec/linear-optical-isolation-for-safe-sensor-operation

Best regards.

[Signal]

My purpose is to use it as a voltage controlled  resistance in an application.

Could you add more specifics about your application?