[Coco] "New" Coco 1 with keyboard and composite adapter

[Gene Heskett]

On Friday 13 March 2015 11:14:28 Al Hartman wrote:
> Yes, thank you Luis!
>
> Just ordered 5 of them on eBay for under $3.00 US. I figure 3 out of 5
> should be good.

At that price, I'd expect them all to be good.

But, bear in mind that the TL081 is a bifet input, drawing sub picoamp 
input bias currents.  As such, they are subject to the normal breakdown 
mechanisms of CMOS circuitry, but with IIRC, clamping diodes that with 
reasonable source impedances, will clamp the inputs to not below 
the  -vcc rail to not above the +vcc rail.

Capable of decent output currant drives, I used a big sack of the 
TL084's, its 4 in a pack version, as audio distribution amplifiers at 
WDTV for nearly 16 years of my 18 year tour there.  In that service, and 
with a 255 foot tower in the back yard collecting every lightning strike 
in the neighborhood, the considerable EMP from one of those events, did 
take its toll on the output stages, which were not so clamped.  That 
made a 200 foot run to something else a great EMP antenna, so I never 
had less than 20 in stock.  However, with their gain-bandwidth product 
running at a nominal gain of 2, we had much less overall distortion than 
in anything we could buy commercially, and a high end bandwidth that 
could show just how big a piece of power hungry junk the famous 5532 
op-amp really was. With +-15 volt supplies, locally regulated on the 
individual cards, I was justifiably proud of the sound we broadcast.  
They could make 29 volts peak to peak at a distortion of 0.02%.  That 
was the distortion of the homemade state variable generator we also 
built inhouse.  Normal operating levels were in the 1 or 2 volt peak to 
peak range.

Cheers, Gene Heskett
-- 
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