[sdiy] Happenin' new opamp

[Tim Ressel]

I pretty much use just 2 amps now; the 1678/9 any time I need 
performance, and the TL082/4 for generic stuff. My new filter module is 
a good example: 1678 for the audio processing and a TL082 for CV processing.

In a way it feels funny to reduce the huge universe of op amps down to 2 
parts. I know there are many applications where other amps are better. 
High power, high voltage, high accuracy, high frequency, etc. But for 
what I tend to do these two pretty much cover it. Many thanks for the 
dudes who came up with it!

--Tim (parts nerd) Ressel


On 4/19/2018 8:15 AM, Steve Lenham wrote:
> I too designed the 1678 into a new product after Tim's original post 
> drew it to my attention, and they work very nicely.
>
> The power of networking, eh - wonder if it will catch on?
>
> Cheers,
>
> Steve L.
> Benden Sound Technology
>
>
> On 19/04/2018 15:40, Matthias Herrmann wrote:
>> Nice.
>> I use the OPA1678 as my new working horse for quite a while now.
>>
>>     *From: *Synth-diy <synth-diy-bounces at synth-diy.org
>>     <mailto:synth-diy-bounces at synth-diy.org>> on behalf of Mattias
>>     Rickardsson <mr at analogue.org <mailto:mr at analogue.org>>
>>     *Date: *Thursday, 19 April 2018 at 14:16
>>     *To: *Tim Ressel <timr at circuitabbey.com 
>> <mailto:timr at circuitabbey.com>>
>>     *Cc: *Synth DIY <synth-diy at synth-diy.org
>>     <mailto:synth-diy at synth-diy.org>>
>>     *Subject: *Re: [sdiy] Happenin' new opamp
>>
>>     I'm throwing in some news (for me at least) about the fairly new
>>     OPA1678/79 low-noise rail-to-railFET-input op-amps that I was trying
>>     as substitutes for the OPA1652/54, which has a price more than twice
>>     as high. The specifications are remarkably similar, and by accident
>>     I got in contact with TI's John Caldwell. He writes:
>>
>>     "I’ll let you in a on a little secret, the silicon is identical
>>     between the two devices. OPA1652 was released by another engineer
>>     before me, and when I took over the portfolio of audio op amps I
>>     personally felt that OPA1652 was too expensive to address the bulk
>>     of audio opportunities. For that reason, we made some changes to the
>>     production testing (used new test hardware that let us test more
>>     units faster) to reduce the manufacturing cost and re-released the
>>     device at a lower price point.
>>     Fun fact: the OPA1652 / OPA1678 has the lowest broadband voltage
>>     noise of any FET-type input amplifier in TI’s portfolio. It even has
>>     lower broadband voltage noise than the much more expensive OPA827."
>>
>>     I don't know if this was known before, but anyway great to have the
>>     same brilliant chip for a fraction of the price... and isn't it a
>>     great attitude about quality product sales? :-)
>>
>>     Regarding the inputs, which they don't mention being FET in the
>>     OPA1678 datasheet:
>>
>>     "We received your feedback on the OPA1678 datasheet. With regards to
>>     mentioning the input device type, the OPA1678 is fabricated on a
>>     CMOS process, so yes the device type is indeed a FET (MOSFET). This
>>     is also shown in the simplified diagram of the internal architecture
>>     on the first page.
>>     Calling it a “FET” input sometimes raises confusion between whether
>>     or not the devices is JFET or CMOS and I wanted to avoid that when I
>>     wrote the OPA1678 datasheet."
>>
>>     /mr
>>
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-- 
--Tim Ressel
Circuit Abbey
timr at circuitabbey.com