Hey everyone I need to scale down my signal voltage for something. My signal is analog sign wave which fluctuates between .3v and .9v at about 1hz. Low current under 30ma

I need a device which is adjustable to scale down the voltage BY 0mv to 300mv or even more. In other words if an adjustable voltage drop diode existed it would be perfect.

There are so many cheap mass manufactured modules on the market today and I can't seem to find anything simple/cheap to do this

 

hi mvall,
Welcome to AAC.
Are you asking how to level shift 0.3v thru 0.9v down to 0v thru 0.3v, is that correct.?
E

 

No I need to shift it down BY 0 to 300mv. So say with a Potentiometer be able to turn a sign wave that fluctuates between 300mv and 900mv to:

0mv and 600mv
...
100mv and 700mv
...
200mv and 800mv
...
300mv and 900mv

 

Hi myall, from your description it sounds like you can do the job with a simple Op amp circuit - Gain of one, with your required offset fed into the negative input to the opamp, sine wave on the positive:


You could also do it passively by "adding" a negative voltage with a potential divider circuit but this would require a negative voltage supply which is a bit more complicated.

 

You need to attenuate and offset, case in this ap note -

http://www.ti.com/lit/an/sloa030a/sloa030a.pdf


Regards, Dana.