| Author |
Message |
jasen
electronics forum Guru Wannabe
Joined: 18 Jun 2006
Posts: 204
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 Posted: Wed Jun 28, 2006 8:49 am Post subject:
Re: Summing non inverting op amp.
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On 2006-06-27, daveatfernie <Daveatfernie@gmail.com> wrote:
| Quote: | Hi,
I've a voltage change 3-4 Volts which I need to change into a 0 to 4
Volt signal.
I have used an inverting op-amp with a virtual ground to give a
cracking result but unfortunately the voltage is going the wrong way
(decreasing instead of increasing.
I have changed to circuit over to be a non inverting amplifier but I'm
worried about the virtual ground. I've been told that summing in a non
inverting op amp can be difficult.
|
do you need a virual earth or summing amp?
| Quote: | I took the series resistors out of the circuit from my virtual ground
(created from a pot) and from the voltage that I'm amplifying. I have
a 560K feedback and 220K to ground giving me a gain of around 3.5.
Will I have problems with the virtual ground being amplified to or any
other problems?
|
huh?
Your description of the problem seems to call for something like this.
|\
in------------|+`\
| >---+------>
.--|-,/ |
| |/ |
| |
4V--[110K]-+---[330K]-+
Bye.
Jasen |
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daveatfernie
electronics forum beginner
Joined: 02 May 2006
Posts: 5
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| Posted: Tue Jun 27, 2006 9:05 am Post subject:
Re: Summing non inverting op amp.
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If I was to conect my ground resistor to my virtual ground would this
be a better circuit. I'm now worried that my offset voltage from the
virtual ground will also be amplified by the op amp.
Cheers again
David |
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daveatfernie
electronics forum beginner
Joined: 02 May 2006
Posts: 5
|
| Posted: Tue Jun 27, 2006 8:42 am Post subject:
Summing non inverting op amp.
|
|
|
Hi,
I've a voltage change 3-4 Volts which I need to change into a 0 to 4
Volt signal.
I have used an inverting op-amp with a virtual ground to give a
cracking result but unfortunately the voltage is going the wrong way
(decreasing instead of increasing.
I have changed to circuit over to be a non inverting amplifier but I'm
worried about the virtual ground. I've been told that summing in a non
inverting op amp can be difficult.
I took the series resistors out of the circuit from my virtual ground
(created from a pot) and from the voltage that I'm amplifying. I have
a 560K feedback and 220K to ground giving me a gain of around 3.5.
Will I have problems with the virtual ground being amplified to or any
other problems?
Many thanks in advance.
David |
|
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