Voltage Amplifier?

[dmt1]

Hi

Just wondering if there is any device that would allow me to amplify a
voltage by 1 log unit (ie. a factor of 10). I have something that is
outputing at approx 0.045VDC but the sensor will only detect if it is
in the order of 0.45VDC. I don't know the reason for the descrepancy
but i was just wondering if there is anything i can do to amplify the
output signal?

Thanks

 

[Robert Baer]

Hi

Just wondering if there is any device that would allow me to amplify a
voltage by 1 log unit (ie. a factor of 10). I have something that is
outputing at approx 0.045VDC but the sensor will only detect if it is
in the order of 0.45VDC. I don't know the reason for the descrepancy
but i was just wondering if there is anything i can do to amplify the
output signal?

Thanks

A good linear solution is to use an operational amplifier, with the
gain set to 10.
You can have a gain of either +10 or of -10 as you wish.
Op amp ICs are cheap as heck, resistors toset the gain are also very
cheap.
The power supply could be as meager as a single 9V battery, or a 10 to
30V wall wart, or a special +15V / -15V supply.

 

[JeffM]

amplify a voltage by 1 log unit (ie. a factor of 10)

dmt1

http://images.google.com/images?&q=opamp1+gain-10

 

[Robert Stankowic]

Hi

Just wondering if there is any device that would allow me to amplify
a voltage by 1 log unit (ie. a factor of 10). I have something that
is outputing at approx 0.045VDC but the sensor will only detect if
it is in the order of 0.45VDC. I don't know the reason for the
descrepancy but i was just wondering if there is anything i can do
to amplify the output signal?

Thanks

Depends on the type of signal and the required precision. Your
question lets me guess that it is low frequency and the precision is
not critical, in this case any cheap OpAmp will do:


|\
-IN to +INPUT ----| \_________________OUT
----|1K|----| / |
| | |/ |
| | |
GND | |
----|10K|-----
If it must be adjustable
use a trimpot here

Most of them work with supply voltages from +/-3 to +/- 18 VDC
For higher precision/frequency get the datasheet of the OpAmp, many of
them have circuit examples.

 

[Ben Moss]

Actually that should be a 9K ohm, not a 10K (when you use the positive
input the gain is 1 + R2/R1). A trimpot is still a good idea,
considering tolerances of typical resistors.



|\
-IN to +INPUT ----| \_________________OUT
----|1K|----| / |
| | |/ |
| | |
GND | |
----|9K|------
If it must be adjustable
use a trimpot here

HTH,
-Ben

 

[Robert Stankowic]

Actually that should be a 9K ohm, not a 10K (when you use the positive
input the gain is 1 + R2/R1). A trimpot is still a good idea,
considering tolerances of typical resistors.



|\
-IN to +INPUT ----| \_________________OUT
----|1K|----| / |
| | |/ |
| | |
GND | |
----|9K|------
If it must be adjustable
use a trimpot here

HTH,
-Ben

Of course. Thank you for pointing that out.

 

[JeffM]

that should be a 9K ohm

Ben Moss

or you could specify values that are actually available
(no matter the tolerance).
http://www.token.com.tw/resistor/resistor-color-code.htm

|\
-IN to +INPUT ----| \_________________OUT
---- 2K ----| / |
| | |/ |
| | |
GND ---- 18K ------