OK Alex.
try
I've adjusted the gains etc to be close to your needs - some
adjustment may still be required. I set the second input at 15.4V as
this is 100x the 154mV for input1. Reduce R27 for more input2 gain if
you need it.
The output load of 20ohms will be a problem - the opamp probably won't
work too well into that low a load. 6V pk-pk into 20 ohme works out at
about 330mA pk-pk.
Also the frequency low end response is limited by the transformer.
You'll need to check the exact parameters of your transformer to get
a good estimate.
Re the opamp - apart from the output current, I'm not sure what to
suggest. Add in a proper audio output amp chip perhaps. Or include a
simple 2 or 3 transistor output stage, similar to your earlier input
amplifier.
Hope this assists.
Richard
On 12 October 2012 20:19, Alexander Winnig
wrote:
> Am 12.10.2012 05:34, schrieb Richard Prosser:
>> Ciruit2 should be OK with a few tweaks.
>>
>> But some questions arise also.
>> 1. what is the frequency range of interest?
> 10 Hz to 20 kHz.
>> 2 The desired 3V output - is that pk-pk or rms?
> Vpp =3D 6V. This is the MAX! It shouldn't be reached when the input signa=
l
> is at max, it should be around Vpp =3D 4V to 5V then.
>> 3. What are the actual input signal levels?
> Vpp before transformer should be 0.154V or 154mV max.
>> 4. What is the supply? If it is a 9V battery, then your 30ohm biasing
>> resistors are going to drain it fairly quickly.
> Yes I am.
>> Better to use higher
>> value resistors and bypass with 10uF or larger caps.
>>
>> Other Comments:
>> You have the transformer turns ratio set at 1. This isn't in
>> accordance with your 1.6:1 statement above.
> On my transformer there is "1:6, RPrim =3D 4.6 Ohms, RSek =3D 180 Ohms".
>
> Do you mind modifying my circuitry (
> https://www.circuitlab.com/circuit/ru78q2/zusammenfugen/ ) using your
> ideas and republishing it? Makes this conversation a lot easier.
>> Are you actually going to use a '741? If you are, then you will have
>> limited gain for any reasonable frequency range. And noise may be an
>> issue also.
> I have
>
> LM358
> LM393
> 741CN
> LM2901N
>
> at my disposal. Which one would you recommend? Or would you rather
> recommend building an amplifier the way I did in the first schematic ie
> using transistors?
>
> Alex
>>
>> RP
>>
>>
>>
>> On 12 October 2012 16:06, Alexander Winnig
>> wrote:
>>> Both signal sources are being shown at max amplitude. My goal is to mix=
them
>>> so each signal source has the same volume and the final result is not t=
o
>>> exceed 3 volts.
>>>
>>> Here's the current schematic.
>>>
>>> https://www.circuitlab.com/circuit/x6hjxg/verst2/
>>>
>>> Feel free to modify and repost the link.
>>>
>>> But I thought that maybe I can save a lot of components and do it like
>>>
>>> https://www.circuitlab.com/circuit/ru78q2/zusammenfugen/
>>>
>>> Factor between source one and source two is about 100. Thus the resisto=
r
>>> values R24 and R27 to make them even. But is is not quite satisfactory.=
It
>>> seems that -(V(Transformer)/R27 - V3/R24) * R12 is not -3 Volts as you'=
d
>>> expect from an adding amplifier. Also there's something wrong with the
>>> transformer. It's an 1:6 transformer that should produce about 0.013V o=
n the
>>> output side.
>>>
>>> I am not sure but I guess it is a better approach to optimize circuit 2
>>> rather than the old one.
>>>
>>> Alex
>>>
>>>
>>> Am 12.10.2012 04:05, schrieb Richard Prosser:
>>>
>>> Maybe you meant something more like this? (Minimal Changes and one
>>> input changed to 200Hz to separate the inputs).
>>>
>>> RP
>>>
>>> On 12 October 2012 14:16, Dave Tweed wrote:
>>>
>>> Alexander Winnig wrote:
>>>
>>> I created this https://www.circuitlab.com/circuit/r2kea4/verstarker/
>>> circuit. You can open it and simulate it in your browser, no additional
>>> software needed btw.
>>>
>>> But simulating creates a weird pattern. Is this really the output or
>>> just some flaw in the simulator?
>>>
>>> What you see is an amplifier on the left side and a signal mixer on the
>>> right side. So the result of the first amplifier acts as second source.
>>> Measurement is taken at R15.
>>>
>>> What I see is what looks like the ground node of the mixer connected to=
the
>>> output of the amplifier, and the upper input to the mixer connected to =
the
>>> amplifier's power supply. Surely this isn't what you intended.
>>>
>>> -- Dave Tweed
>>> --
>>> http://www.piclist.com PIC/SX FAQ & list archive
>>> View/change your membership options at
>>> http://mailman.mit.edu/mailman/listinfo/piclist
>>>
>>>
>>>
>>>
>>
>
> --
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.