Voltage controlled resistor circuit question

[Freehawk]

Can anyone please help me with adapting this scheme to 12v single power (in stead of +15 -15v)?

Warm regards

 

[barry]

I never had much luck playing around with that chip, but it looks like you just need to connect the wiper of the pot to +6V, the minus supply input to ground, and the end of the 10K to ground.

 

[Freehawk]

I never had much luck playing around with that chip, but it looks like you just need to connect the wiper of the pot to +6V, the minus supply input to ground, and the end of the 10K to ground.

Thnx for you answer ...

 

[nanosmart]

You could use "Step-Up Voltage Regulator Module" like LM2577 with below circuit:

For your application you need to change several thing:
1-Remove 7805, C11 and C12 .
2-Replace Zener diodes by 1N4746A (18V,1W); If circuit current consumption is higher than 100mA
,you should increase the maximum Power Dissipation of diodes.
3-Replace 7806 by 7815.
4-Replace 7906 by 7915.
5-Increase input voltage up to 35V.

 

[Warpspeed]

I have no idea what the eventual use of this circuit will be, but if you need a fully floating variable resistor, take a look at an H11F1 opto isolator.

May not be what you want, but interesting nevertheless.

https://www.farnell.com/datasheets/1644106.pdf

 

[dick_freebird]

With a series capacitor between the (current source?)
and the upper RX terminal, it doesn't look much like a
resistor to me.

The mentioned photoFET optoisolator is only linear for
maybe +/-100mV and then rolls over. Not a good general
purpose "resistor" for anything but true small signal (as
the datasheet itself makes plain).

I wonder about something like CdS photocells, not so
popular now but once nearly the only game in town;
more of a photoconductivity device, possibly with
some decent linearity. Matched pair of these, matched
pair of LEDs (and matched coupling), one in a feedback
loop and one for the resistor role, would be an isolated
variable resistor.

You might also consider "digi-pot" ICs, which would let
you (duh) control them digitally if that's where the
control ultimately comes from, or use an ADC if you
must have an analog control source.

 

[Warpspeed]

I wonder about something like CdS photocells, not so
popular now but once nearly the only game in town;
more of a photoconductivity device, possibly with
some decent linearity.

An excellent suggestion.
Commonly known these days as a light dependent resistor or LDR.