voltage controlled resistor

Does anyone know of an IC chip for to be used as a variable resistor
whose resistance value may be controlled by varying its voltage input/
signal

 

[Ray King]

Sounds like a fet

<cary.niza@gmail.com> wrote in message
news:1179337478.597465.133360@k79g2000hse.googlegroups.com...

Does anyone know of an IC chip for to be used as a variable resistor
whose resistance value may be controlled by varying its voltage input/
signal

 

[Lostgallifreyan]

"Ray King" <rayjking@bellsouth.net> wrote in
news:TZH2i.6$ij.5@bignews2.bellsouth.net:

cary.niza@gmail.com> wrote in message
news:1179337478.597465.133360@k79g2000hse.googlegroups.com...
Does anyone know of an IC chip for to be used as a variable resistor
whose resistance value may be controlled by varying its voltage input/
signal




Sounds like a fet

Yes. Try the H11F1 optoFET. That can vary from >300 Mohms down to a few
tens of ohms or less, when its LED is fed by an input voltage via a series
resistor. I haven't yet tried it for linearity, but it's a nice idea
because it isolates input and output. If you use the output to drive
another FET, you can probably arrange a near-zero ohms to >300 Mohms
resistor.

 

[Jamie]

cary.niza@gmail.com wrote:

Does anyone know of an IC chip for to be used as a variable resistor
whose resistance value may be controlled by varying its voltage input/
signal

Hmm.

how about a Mosfet ?
or something in the line of a 4066 which does not get
you in the low order of R but can be some what controlled
via voltage.


--
"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

 

[mw]

Yes. Try the H11F1 optoFET. That can vary from >300 Mohms down to a few
tens of ohms or less, when its LED is fed by an input voltage via a series
resistor. I haven't yet tried it for linearity, but it's a nice idea
because it isolates input and output. If you use the output to drive
another FET, you can probably arrange a near-zero ohms to >300 Mohms
resistor.

I just got an email 2 days ago that says the H11F1 was just announced as
discontinued:

"You have purchased the following part number(s) from Digi-Key within
the last two years. The manufacturer has announced this part(s) will
become obsolete. Please click on the link below for more information on
possible substitutes.

FAIRCHILD OPTOELECTRONICS GROUP
Description: OPTOCOUPLER FET BILAT 6-DIP
Manufacturer Part Number: H11F1
Digi-Key Part Number: H11F1-ND"

------------

Maybe it is just the DIP that is gone, I haven't looked into it.

 

[Lostgallifreyan]

mw <mw@avoidspam.com> wrote in
news:Fr63i.3130$4Y.147@newssvr19.news.prodigy.net:

Yes. Try the H11F1 optoFET. That can vary from >300 Mohms down to a
few tens of ohms or less, when its LED is fed by an input voltage via
a series resistor. I haven't yet tried it for linearity, but it's a
nice idea because it isolates input and output. If you use the output
to drive another FET, you can probably arrange a near-zero ohms to
300 Mohms resistor.

I just got an email 2 days ago that says the H11F1 was just announced
as discontinued:

"You have purchased the following part number(s) from Digi-Key within
the last two years. The manufacturer has announced this part(s) will
become obsolete. Please click on the link below for more information
on possible substitutes.

FAIRCHILD OPTOELECTRONICS GROUP
Description: OPTOCOUPLER FET BILAT 6-DIP
Manufacturer Part Number: H11F1
Digi-Key Part Number: H11F1-ND"

------------

Maybe it is just the DIP that is gone, I haven't looked into it.

They're multisourced, I think. I doubt it's entirely obsolete. It better
hadn't be, anyway.

 

[mw]

They're multisourced, I think. I doubt it's entirely obsolete. It better
hadn't be, anyway.

I looked at Fairshild's site... the H11F1, H11F2, and H11F3 are all
listed as lifetime buy. I didn't find any recommendations about
alternatives, except on their obsolete search they recommend "H11F1M",
which doesn't exist.

Nice...