Question re. Operational Amplifiers

Greetings,

I'm really useless at analog circuitry, so any help is appreciated.

I have:

input P0 != GND
input P >= P0
constant A < 1

I would like:

output P* = A (P - P0) + P0

Can and should I use an op-amp for this, or is that overkill?

I know if P0 = GND, then I can just use a resistor to "multiply" by A,
but no such luck.

Thank you for reading.

Regards,

YR

 

[Tim Wescott]

yiminrong@yahoo.ca wrote:

Greetings,

I'm really useless at analog circuitry, so any help is appreciated.

I have:

input P0 != GND
input P >= P0
constant A < 1

I would like:

output P* = A (P - P0) + P0

Can and should I use an op-amp for this, or is that overkill?

I know if P0 = GND, then I can just use a resistor to "multiply" by A,
but no such luck.

R1
___
P o----|___|--.
|
|
o----o (R2 * P + R1 * P0) / (R1 + R2)
R2 |
___ |
P0 o----|___|--'
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)


--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

 

On May 5, 12:41 pm, Tim Wescott <t...@seemywebsite.com> wrote:

yiminr...@yahoo.ca wrote:
Greetings,

I'm really useless at analog circuitry, so any help is appreciated.

I have:

input P0 != GND
input P >= P0
constant A < 1

I would like:

output P* = A (P - P0) + P0

Can and should I use an op-amp for this, or is that overkill?

I know if P0 = GND, then I can just use a resistor to "multiply" by A,
but no such luck.

R1
___
P o----|___|--.
|
|
o----o (R2 * P + R1 * P0) / (R1 + R2)
R2 |
___ |
P0 o----|___|--'
(created by AACircuit v1.28.6 beta 04/19/05www.tech-chat.de)

--

Tim Wescott
Wescott Design Serviceshttp://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details athttp://www.wescottdesign.com/actfes/actfes.html

Thank you. It is much easier than I expected. /YR