Re: Replacement of tcl272

Hi Stefan,

I agree with your (1) to (4) but I do not agree with your last comment that
just because the gain of the amplifier is unity, (input) offset voltages
are not important.

On the contrary, the importance of offset voltages is independent of the
gain of an amplifier.

Raymond Chan

On Thu, Aug 27, 2015 at 6:24 PM, Stefan Jung <[email protected]> wrote:

> Hi Eric
>
> No you can't use a LM301, LM348, LM741, 324, 709, etc.  That would be like
> fitting a spoked, wooden rimmed, road wheel to a Porsche, it wouldn't
> work.  You might as well try an ECC83 - a dual triode valve, for those that
> don't know.
>
> You need an opamp that:
>
> (1) is LOW NOISE (!!!!!)
>
> (2) Has a high input impedance, that means using some sort of FET-input
> opamp.
>
> (3) Can run from a 5V supply.  Most of Noah's Arc opamps can only run from
> about 10-16 or so volts minimum.
>
> (4) Not so important, but you preferably want to use a low power opamp;
> typically drawing not more than 1mA per opamp (just in case you want to
> run from batteries).  This means you will select a relatively slow (for
> todays standard, not Noah's) opamp.
>
> Because you run at unity gain, offset voltages are not important in your
> application.  Rail-to-rail is also not a requirement.
>
> There are many newer and better devices than the TLC272, but if you can't
> get a TLC272, I would just be wasting my time listing more modern (and
> likely more expensive) devices.
>
> Regards
> Stefan
>
>
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