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Title: [REQ]Voltage controlled Potentiometer Post by: itp on June 17, 2016, 09:56:31 09:56 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 Title: Re: [REQ]Voltage controlled Potentiometer Post by: Wizpic on June 17, 2016, 10:42:28 10:42 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
Title: Re: [REQ]Voltage controlled Potentiometer Post by: mars01 on June 17, 2016, 11:54:40 11:54 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 Title: Re: [REQ]Voltage controlled Potentiometer Post by: Crackn on June 17, 2016, 09:29:04 21:29 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. (http://www.iowacitylist.com/Tools-/Hand-Tools-/Vactec-perkins-elmer-VTL9B8-vactrol-opto-lamp-ldr-image.jpg) Title: Re: [REQ]Voltage controlled Potentiometer Post by: metal on June 17, 2016, 10:43:59 22:43 which company makes them now, where do you buy these?
Title: Re: [REQ]Voltage controlled Potentiometer Post by: PICker on June 18, 2016, 05:15:27 05:15 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. Title: Re: [REQ]Voltage controlled Potentiometer Post by: Crackn on June 18, 2016, 09:30:36 09:30 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 Title: Re: [REQ]Voltage controlled Potentiometer Post by: PICker on June 18, 2016, 06:38:50 18:38 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. Title: Re: [REQ]Voltage controlled Potentiometer Post by: bobcat1 on June 19, 2016, 08:27:22 08:27 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 Title: Re: [REQ]Voltage controlled Potentiometer Post by: titi on June 19, 2016, 12:48:09 12:48 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.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 (http://www.digikey.com/en/articles/techzone/2012/dec/linear-optical-isolation-for-safe-sensor-operation) (http://www.digikey.com/en/articles/techzone/2012/dec/~/media/Images/Article%20Library/TechZone%20Articles/2012/December/Linear%20Optical%20Isolation%20for%20Safe%20Sensor%20Operation/article-2012december-linear-optical-isolation-fig5.jpg) Best regards. Title: Re: [REQ]Voltage controlled Potentiometer Post by: Signal on June 19, 2016, 04:50:12 16:50 My purpose is to use it as a voltage controlled resistance in an application. Could you add more specifics about your application? |