summing amplifier with linear offset

[dB]

The


Use a potential divider and pot to get your 0V to 1.6V. Buffer the
voltage from the pot's slider with a unity gain follower (e.g. OP07).
Connect its output to the summing amp through an R equal in value to
the feedback R.

 

[?ine Canby]

Hi all,

Thanks very much for your advice; this is the circuit I've designed ->
http://www.geocities.com/aine_canby/atten.gif

The 15 volt rails are from a regulated source. I wasn't sure about
what resistance to choose for Remit, does 1k sound OK? I also haven't
buffered the AC signal, again does that sound reasonable?

I'm now getting a linear response when the POT (1K) is adjusted, from
about 0 Volts to 1.411 Volts at the output, which I'm happy with.

The output from my circuit will be used to drive a constant current
driver. This driver converts an input voltage to a current. I need to
ensure that I only apply between 0 Volts and 1.6Volts to this driver,
otherwise I will get a current which will damage the equipment I'm
driving. Is there such a this as a 1.5 or 1.6 Volt Zener? Any other
suggestions with regard to this issue?

Thanks again for your help,

Aine.

 

[Ann Canby]

I sorry in advance if I've double posted.

Hi all,

Thanks very much for your advice; this is the circuit I've designed ->
http://www.geocities.com/aine_canby/atten.gif

The 15 volt rails are from a regulated source. I wasn't sure about
what resistance to choose for Remit, does 1k sound OK? I also haven't
buffered the AC signal, again does that sound reasonable?

I'm now getting a linear response when the POT (1K) is adjusted, from
about 0 Volts to 1.411 Volts, which I'm happy with.

The output from my circuit will be used to drive a constant current
driver. This driver converts an input voltage to a current. I need to
ensure that I only apply between 0 Volts and 1.6Volts to this driver,
otherwise I will get a current which will damage the equipment I'm
driving. Is there such a this as a 1.5 or 1.6 Volt Zener? Any other
suggestions with regard to this issue?

Thanks again for your help,

Aine.

 

[Ann Canby]

Woops, sorry about that, here the image embedded in a html page ->

http://www.geocities.com/aine_canby/index.html

 

[Fred Bloggs]

I sorry in advance if I've double posted.

Hi all,

Thanks very much for your advice; this is the circuit I've designed ->
http://www.geocities.com/aine_canby/atten.gif

The 15 volt rails are from a regulated source. I wasn't sure about
what resistance to choose for Remit, does 1k sound OK? I also haven't
buffered the AC signal, again does that sound reasonable?

I'm now getting a linear response when the POT (1K) is adjusted, from
about 0 Volts to 1.411 Volts, which I'm happy with.

The output from my circuit will be used to drive a constant current
driver. This driver converts an input voltage to a current. I need to
ensure that I only apply between 0 Volts and 1.6Volts to this driver,
otherwise I will get a current which will damage the equipment I'm
driving. Is there such a this as a 1.5 or 1.6 Volt Zener? Any other
suggestions with regard to this issue?

Thanks again for your help,

Aine.

Yes- you can use what is called a "clipper"- like so-you can use an
LM324 quad:

Please view in a fixed-width font such as Courier.


+15
| 4.7k
+--/\/\---+
| |
+--------------+
| | |
| | | +-------+
| | | | |\ |
| |\| | +-|-\ |
+--|-\ | | > -+-->Vout
| >--|<|---+-----|+/
Vin >-------------|+/ 1N4148| |/
from |/| |
summer -15 |
|
|
+--------------+
| |
| |
| +15 |
| |\| |
+--|-\ |
| >--|<|---+
1.6VDC >----------|+/ 1N4148
LIMIT |/|
-15

 

[Fred Bloggs]

Yes- you can use what is called a "clipper"- like so-you can use an
LM324 quad:

Please view in a fixed-width font such as Courier.


+15
| 4.7k
+--/\/\---+
| |
+--------------+
| | |
| | | +-------+
| | | | |\ |
| |\| | +-|-\ |
+--|-\ | | > -+-->Vout
| >--|<|---+-----|+/
Vin >-------------|+/ 1N4148| |/
from |/| |
summer -15 |
|
|
+--------------+
| |
| |
| +15 |
| |\| |
+--|-\ |
| >--|<|---+
1.6VDC >----------|+/ 1N4148
LIMIT |/|
-15

Cascade a second clipper to keep Vout>=0V like so:

Please view in a fixed-width font such as Courier.





+15
| 4.7k
+--/\/\---+
| |
+--------------+ +--------+
| | | | |
| | | +----------+ | |\ |
| | | | |\ | +---|-\ |
| |\| | +-|-\ | | >-+>Vout
+--|-\ | | >-|>|-+------|+/
| >--|<|---+----|+/ 4148| |/
Vin >-------------|+/ 1N4148| |/ |
from |/| | /
summer -15 | 1k
| /
| \
+--------------+ |
| | |
| | ---
| +15 | ///
| |\| |
+--|-\ |
| >--|<|---+
1.6VDC >----------|+/ 1N4148
LIMIT |/|
-15