diyAudio (
-   Solid State (
-   -   convert voltage to resistance? (

geom_tol 17th December 2004 09:51 PM

convert voltage to resistance?
Anyone have ideas on how to convert a voltage into a resistance?

I searched around, but found only digital solutions, looking for something analogue.


darkfenriz 17th December 2004 09:54 PM

a FET transistor maybe?
kind of converts gate-to-source voltage to drain-to-source resistance
but it is very unlinear
what do you need it for?

sivan_and 18th December 2004 04:05 AM

Voltage controlled attenuator or Voltage controlled amplifier,
Related post:

:) :)

Eva 18th December 2004 05:46 AM

Search the internet for 'light dependent resistors' or 'LDR'. This is a special kind of resistors whose value change depending on how much light intensity they are receiving

Also there are LDR + LED combos in a single package perfectly isolated from ambient light, they are sometimes used in the limiter sections of PA amplifiers, altough these parts are hard to find

The smartest feature of LDRs is that no electrical connection between the resistor part and the light-emitting part is required

sivan_and 18th December 2004 09:21 AM

EVA !! The post was for Voltage depended resistor as discribed by darkfenriz, not Light depended resistor.

Enzo 18th December 2004 09:39 AM

The LDR is a resistor the value of which can be controlled by the current through the LED inside. It is not difficult to convert a voltage to a varying current through an LED. I think it is a good suggestion.

We use Vactrol LDRs in guitar amps all the time. They serve as signal routing switches and as tremolo interfacecs.

Google Vactrol and you ought to find them easy enough.

Or make your own. Photoresistor and a light bulb wraped up in something light tight. Drive the bulb with your voltage and the resistance of hte photocell varies.

geom_tol 18th December 2004 04:57 PM

Thanks for the ideas! I did find some info about optocouplers (same thing as the ldr + led I guess) previously, I'll look into it in more detail.

Here's a brief description of exactly what I'm trying to do.

I used to have a potentiometer that drove a gauge. But now I want to replace the potentiometer with a Hall effect rotary sensor (these have come down in price alot recently). The Hall effect sensor outputs a voltage.
The gauge is an industry standard gauge that is driven by a variable resistance. I cannot change the gauge.

The voltge to resistance conversions does need to be linear for a good reading on the gauge.

Thanks again for the ideas.

peranders 18th December 2004 05:41 PM


A measuring instrument for measuring and indicating a quantity or for testing conformity with a standard.

What was this gauge for and what was the resistance controlling?

Why do I ask? Maybe you can use a voltage or a current to control?

jcx 18th December 2004 05:47 PM

you might check the display spec more closely, if it isn't poteniometric (voltage sensing) then it almost certainly responds to current drawn by the sense resistor from a fixed voltage, you could just put in(or sink) a voltage controlled current

a very few circuits might use a resistor to control an internal oscillator and use a frequency counter type display

i missed the part about this being about solid state audio amplifiers however

Enzo 20th December 2004 07:18 AM

He wants us to Amplify on his situation. Once he has Solid advice his State of mind will improve.

All times are GMT. The time now is 05:25 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 18.75%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio