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-   -   Have an offset for 2V with OPA2134 (http://www.diyaudio.com/forums/analog-line-level/63287-have-offset-2v-opa2134.html)

Progg70 27th August 2005 11:05 PM

Have an offset for 2V with OPA2134
 
If I have an OP with no possibility to adjust the output offset. How can I then have about 2V offset? Iím looking for a nice circuit solution. I have one OP for the input and another like a driver before the output stage. The Output stage need a offset for about 1.9V to have 0V on the output. I use the OP OPA2134.

regard

Progg70

BrianL 27th August 2005 11:12 PM

You need to give some useful information if you expect
help. At a minimun, a circuit diagram would be instructive.

Progg70 28th August 2005 07:40 AM

2 Attachment(s)
Good morning!

OK! I have now an attachment with the circuit. I need a offset for + 2V on the output.
Regard

Progg70

peranders 28th August 2005 03:21 PM

If you have an AC coupled output you won't get any offset at all.

If you tell us the application it may be easier to understand what you are after.

Progg70 28th August 2005 05:10 PM

2 Attachment(s)
OK! My mistake! You can skip the capacitor at the end, they was there from the beginning.

So, the output is the DC-coupled and I need to have the audio signal +2V offset.
The output signal is going to have about 20V top-top. If someone can tell me a nice configuration to adapt to this circuit Iím really happy.

Regard
Progg70

wa2ise 29th August 2005 08:17 AM

To create a +2V offset on the output, move the 10K resistor R6 from ground to a clean source of -3/4 volt. What this does is to draw current from the output, thru the 27K feedback resistor, and then on to the 10K resistor to the -0.75V supply. The op amp's inverting input is kept at 0V, and thus the output willo to +2V. The audio signal is amplified as before. This is essentially an adder circuit.

Progg70 29th August 2005 02:31 PM

Tanks! Exactly what i needed.
Iím going to try it in the afternoon.
Now I hope my small single end-amp. will bee ready for a first test to the weekend.

Regard

Progg70

Progg70 30th August 2005 07:19 AM

Yes!
 
Yes!
Itís working very nice. I have de circuit ready now so Iím starting with the PCB.

Thanks

Progg70


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