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Need a isolated adjustable device to raise signal voltage from .2~.8v --> ~.2~1.0v

supak111

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Apr 29, 2012
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Hey everyone need to make a device to raise my signal voltage. My signal voltage varies between .2~.8v, I need to be able to add 0~.2 volt to this signal making it .2~1.0 volts total. So basically the user can adjustable to add extra 0volt to .2 volts. This is a very low current circuit, under 20ma. Also it should be isolated.

I'ma newbe so I have no clue how one would go about this besides adding a battery with .2volts in series with the signal voltage which i think would work but it would not be adjustable and i would need to change the battery...

Few ideas I've had:
Usa a small solar cell inline with the signal voltage and vary the amount of light the solar cell see to vary the raised voltage... But this seems like a super slow circuit and not sure if the original signal voltage of .2v~.8v would go though the solar cell in the first place...

Any other ideas?
 

Harald Kapp

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Look up operational amplifier adder circuits.
 

supak111

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Oh thanks, thats super easy then

And to isolate the whole thing i'll just buy a isolated transformed type 5v power supply I think is the easiest/cheapest way
 

danadak

Feb 19, 2021
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Tools to manage the OpAmp G calculations -





By the way, if you are using Arduino to look at the V there is a f() call to translate
a range :



Regards, Dana.
 

supak111

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Voltage is coming of a vehicle OxySensor
 

crutschow

May 7, 2021
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Here's the LTspice simulation of an circuit using two op amps (or one dual) to generate the offset:
Pot U3 adjusts the offset from 0V to +0.2V.

1662792149719.png
 

Bluejets

Oct 5, 2014
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Oxygen sensors and ECU's are not the kind of device you should be playing with if part of the vehicle.
That plus one could do some real damage if the altered signal says it's a rich mixture and the ECU decides to lean out the mixtures, which is more than likely what it will do.
 

supak111

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I'm not going to lean anything out (well I am but thats what I want, I'm adding a supplemental fuel...) don't worry. Just a simple experiment and besides I have a wideband 02 sensor / gauge in my vehicle not to mention I tune cars as a hobby so I'm well versed but thanks for the heads up for anyone else attempting this...
 

Bluejets

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If you increase the voltage coming from the sensor, that will tell the ECU the engine is rich (when it probably isn't)
Reaction from the ECU will be to lean out the engine (regardless if you want it or not)
Everyone who is anyone in the know, knows what lean mixtures do to engines.

Keep an eye peeled for the vehicle inspection mob........they don't take too kindly to those who think they know better.
Especially when you start playing with environmental issues.
 

supak111

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I'm adding hydrogen to the intake which makes the engine run rich, hence why I need this test device
 

Bluejets

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I'm adding hydrogen to the intake which makes the engine run rich, hence why I need this test device

Hehehehehe...ok

Just let everyone know when you are about to open the tap and we'll all wait for the boom.

I fear the moon is full once again.......
 

supak111

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Haha will do! I will be recording the whole thing so if it does it should make for an interesting YT video lol
 
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