Sonsivri
 
*
Welcome, Guest. Please login or register.
Did you miss your activation email?
December 06, 2016, 11:08:47 11:08


Login with username, password and session length


Pages: [1]
Print
Author Topic: [REQ]Voltage controlled Potentiometer  (Read 665 times)
0 Members and 1 Guest are viewing this topic.
itp
Junior Member
**
Offline Offline

Posts: 58

Thank You
-Given: 188
-Receive: 20


« on: June 17, 2016, 10:56:31 10:56 »

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
Logged
Wizpic
Global Moderator
Hero Member
*****
Offline Offline

Posts: 976

Thank You
-Given: 197
-Receive: 344



« Reply #1 on: June 17, 2016, 11:42:28 11:42 »

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
Logged

When you think, "I can't do anymore. I need a break," that is the time to challenge yourself to keep going another five minutes. Those who persevere for even an extra five minutes will win in life..
mars01
Junior Member
**
Offline Offline

Posts: 51

Thank You
-Given: 106
-Receive: 82


« Reply #2 on: June 17, 2016, 12:54:40 12:54 »

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

« Last Edit: June 17, 2016, 01:03:32 13:03 by mars01 » Logged
Crackn
Active Member
***
Offline Offline

Posts: 106

Thank You
-Given: 71
-Receive: 408



« Reply #3 on: June 17, 2016, 10:29:04 22:29 »

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.

Logged
metal
Global Moderator
Hero Member
*****
Offline Offline

Posts: 2018

Thank You
-Given: 514
-Receive: 477


Top Topic Starter


« Reply #4 on: June 17, 2016, 11:43:59 23:43 »

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

nothing to say..
PICker
Junior Member
**
Offline Offline

Posts: 75

Thank You
-Given: 28
-Receive: 35


« Reply #5 on: June 18, 2016, 06:15:27 06:15 »

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.
Logged
Crackn
Active Member
***
Offline Offline

Posts: 106

Thank You
-Given: 71
-Receive: 408



« Reply #6 on: June 18, 2016, 10:30:36 10:30 »

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


Logged
PICker
Junior Member
**
Offline Offline

Posts: 75

Thank You
-Given: 28
-Receive: 35


« Reply #7 on: June 18, 2016, 07:38:50 19:38 »

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.
Logged
bobcat1
Active Member
***
Offline Offline

Posts: 151

Thank You
-Given: 1126
-Receive: 29


« Reply #8 on: June 19, 2016, 09:27:22 09:27 »

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

Logged
titi
Active Member
***
Offline Offline

Posts: 192

Thank You
-Given: 1434
-Receive: 705



« Reply #9 on: June 19, 2016, 01:48:09 13:48 »

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.digikey.com/en/articles/techzone/2012/dec/linear-optical-isolation-for-safe-sensor-operation

Best regards.
Logged
Signal
Active Member
***
Offline Offline

Posts: 102

Thank You
-Given: 47
-Receive: 33


« Reply #10 on: June 19, 2016, 05:50:12 17:50 »

My purpose is to use it as a voltage controlled  resistance in an application.
Could you add more specifics about your application?
Logged

Give a right name to a right game and play it right
Pages: [1]
Print
Jump to:  


DISCLAIMER
WE DONT HOST ANY ILLEGAL FILES ON THE SERVER
USE CONTACT US TO REPORT ILLEGAL FILES
ADMINISTRATORS CANNOT BE HELD RESPONSIBLE FOR USERS POSTS AND LINKS

... Copyright 2003-2999 Sonsivri.to ...
Powered by SMF 1.1.18 | SMF © 2006-2009, Simple Machines LLC | HarzeM Dilber MC