Convert 0 - +5 volt input signal to -5 - 0 volt output.

Thread Starter

LenoB

Joined Jun 22, 2018
4
I am using DAC1 on an Arduino Duo board to create a waveform that runs 20 hz and varies from 0 to 5 volts. I want to shift the output from 0 - +5 volts to -5 - 0 volts. Have tried several different op amp circuits and nothing is working for me. seems like it should be a fairly simple thing to do but the solution is eluding me.
 

crutschow

Joined Mar 14, 2008
26,969
Do you have a negative supply voltage for the op amp?
You need that obviously to get a negative output voltage, since op amps can't output a voltage greater than their supply voltages.

Just connect an inverting op amp circuit with a gain of -1 to a plus and minus supply of adequate voltages for your op amp.
That will give you the desired signal out.
 

Thread Starter

LenoB

Joined Jun 22, 2018
4
Do have Duel power supply.
The info for the Arduino DUO says "Please note that DAC output range is actually from 0.55 V to 2.75 V only.". So I am not going to get a 0-+5 volt output. So looking for a circuit that will convert the .55-2.75 volt signal to a -5 to 0 volt signal. I have Function generators that provides and offset adjustment that allows the user to adjust the output signal up or down without affecting the gain.
 

danadak

Joined Mar 10, 2018
4,057
Basically a summer with G is what you need.

Do you want .55 to 2.75 translated to 0 to -5 or
- 5 to 0 ? In other words as input to summer increases
do you want its output to go more negative or less ?

Look at summer and diff subtractor circuits -

https://www.ti.com/seclit/sl/slyy137/slyy137.pdf

If your supplys are +5 and -5 use RRIO opamp.
Otherwise use supplies that meet CM requirements
of opamp and design.


Regards, Dana.
 

Thread Starter

LenoB

Joined Jun 22, 2018
4
Input Signal starts at 2.75 volts and decays to .55 volts. Want the output to start at 0 volts and decay to -5 volts...
 

Thread Starter

LenoB

Joined Jun 22, 2018
4
Thank you so much. The dawn breaks through. Unipolar to bipolar worked out great.
Thank you to all for your help.
LenoB
 
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