Have an offset for 2V with OPA2134

Progg70 · 27th August 2005, 10:05 PM

If I have an OP with no possibility to adjust the output offset. How can I then have about 2V offset? I’m 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, 10:12 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, 06:40 AM

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, 02:21 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, 04:10 PM

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 I’m really happy.

Regard
Progg70

wa2ise · 29th August 2005, 07:17 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, 01:31 PM

Tanks! Exactly what i needed.
I’m 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, 06:19 AM

Yes!
It’s working very nice. I have de circuit ready now so I’m starting with the PCB.

Thanks

Progg70

27th August 2005, 10:05 PM	#1
Progg70 diyAudio Member Join Date: Jul 2004 Location: Sweden	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? I’m 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

27th August 2005, 10:12 PM	#2
BrianL diyAudio Member Join Date: Mar 2002 Location: USA	You need to give some useful information if you expect help. At a minimun, a circuit diagram would be instructive. __________________ bel

28th August 2005, 02:21 PM	#4
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	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. __________________ /Per-Anders (my first name) or P-A as my friends call me

30th August 2005, 06:19 AM	#8
Progg70 diyAudio Member Join Date: Jul 2004 Location: Sweden	Yes! Yes! It’s working very nice. I have de circuit ready now so I’m starting with the PCB. Thanks Progg70

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29th August 2005, 07:17 AM	#6
wa2ise diyAudio Member Join Date: Apr 2005 Location: NJ	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.

29th August 2005, 01:31 PM	#7
Progg70 diyAudio Member Join Date: Jul 2004 Location: Sweden	Tanks! Exactly what i needed. I’m 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

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