Change of voltage level from 3.3 to 7 V in to 0-5 V( need urgent help)

[shekhar87]

Hi,
I am designing an application and i am stuck on 1 part. I need to change my voltage level from 3.3- 7V in to 0-5 V.
What can i do ?
Please reply :grin:

---------- Post added at 11:58 ---------- Previous post was at 11:35 ----------

This is dc voltage...folks give your inputs....i really need it

 

[umesh49]

If it was what the votlage level need to change then you can use a comparator with 3.3V reference switch point and use the comparator outpur to drive a simple transistor based NOT gate with 5V pullup.

 

[shekhar87]

@ Umesh :Can you help me with circuit?
The input range is 3.3-7v and i want output of 0-5v. (it is a dc input and output)

 

[alexan_e]

If you want all the values between 0-5 (range) and not just 0v or 5v then you can use a differential amplifier.
something like this should work



input to V2
3v3 to V1 (to apply negative offset)
gnd to Vr

the gain should be about 1.35 (RF/R1 ratio) so that the 3.7v input variation is translated to 0-5v

Alex

 

[shekhar87]

@Alex: i want to change 0-5v (range) to 3.3-7v (range).
will this circuit help?
Please guide me

 

[alexan_e]

in the first post you said from 3.3- 7V in to 0-5 V, is it the opposite?

in that case you need a 0.74 gain (RF/R1)
gnd to V1
input to V2
3v3 to Vr

this will add an offset of 3v3 and a gain of 0.74 so for example 5v in will become 5v*0.74 = 3.7v+ 3v3=7v
or 0v*0.74=0v+3v3=3v3

Alex

 

[mkspencer]

I tried this circuit and didn't have much luck with an LT1819. The input is .5Vpp 2.5V offset going to a 1Vpp with .5Voffset.
I tied V1 to 2.25V
Input to V2
set the gain to 2 because of the 1 to .5 v variation?

Matt