Re: Offset voltage on voltage follower
From: CFoley1064 (cfoley1064_at_aol.com)
Date: 08/19/04
- Next message: Robert C Monsen: "Re: bps to hex"
- Previous message: John Fields: "Re: Marriage is under fire!!"
- In reply to: tuurbo46: "Offset voltage on voltage follower"
- Next in thread: Jonathan Kirwan: "Re: Offset voltage on voltage follower"
- Reply: Jonathan Kirwan: "Re: Offset voltage on voltage follower"
- Messages sorted by: [ date ] [ thread ]
Date: 19 Aug 2004 19:05:09 GMT
>Subject: Offset voltage on voltage follower
>From: tuurbo46@yahoo.co.uk (tuurbo46)
>Date: 8/19/2004 11:27 AM Central Daylight Time
>Message-id: <9ded7dd7.0408190827.622ee9bf@posting.google.com>
>
>Hi
>
>I need a bit of help on a circuit im trying to build. I will try to
>explain my problem below.
>
>Circuit requirements:
>
>*input to op-amp = 0 to 5v
>*output from op-amp = 0.5v to 3.5v
>
<snip>
>Any ideas?
This type of thing is called level shifting. You might want to try something
like this (view in fixed font or M$ Notepad):
Summing Op Amp Level Shifter
Vin(0-5V)
___
o-|___|-o---.
2K | |
3K.-. | .----------.
+5V | | | | VCC |
+ | | | | + |
| '-' | | |\| |
.-. | | '---|-\ |
18K| | === | ___ | >---o
| | GND '-|___|--o---|+/ Output (0.5V to 3.5V)
'-' 33K | |/|
| ___ | VEE
o----------|___|--'
| 33K
.-.
2K| |
| |
'-'
|
===
GND
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de
(By the way, the shareware program AAC is a good way to do this rather than
listing nodes)
Looking at the circuit above, you can see that your 0-5V signal is attenuated
to a 0-3V signal (the span of your final output is 3V) by the 2K/3K divider.
Then you add 0.5V with the 18K/2k divider. The two identical 33K resistors
cause a summing action to get your 0.5 to 3.5V. This is buffered by your
CA3140 set as a voltage follower to give you a low impedance output. Use 1%
resistors for better accuracy.
Good question. The non-inverting summing amplifier is your friend. One of the
best basic tutorials on how to use op amps is National Semiconductor's App Note
31.
http://www.national.com/an/AN/AN-31.pdf
Read it -- a lot of what you need to use op amps is right there.
Good luck
Chris
- Next message: Robert C Monsen: "Re: bps to hex"
- Previous message: John Fields: "Re: Marriage is under fire!!"
- In reply to: tuurbo46: "Offset voltage on voltage follower"
- Next in thread: Jonathan Kirwan: "Re: Offset voltage on voltage follower"
- Reply: Jonathan Kirwan: "Re: Offset voltage on voltage follower"
- Messages sorted by: [ date ] [ thread ]
Relevant Pages
|
