[sdiy] Discrete OTA (Barrie, xkcd)

[The Old Crow]

   The flavor text on that xkcd has the author admitting he tried to 
work out the value of the resistor net.  In one of the late-70s issues 
of Popular Electronics, before it was ruined by the title change (to 
Computers and Electronics), Forrest Mims has a resistor lattice 
challenge that was very similar: it was an "infinite" lattice of 1-Ohm 
resistors, with an ohmmeter across one of them, which the challenge 
being to fill in the measured value.

   Randall Munroe's resistor lattice is triangular, not square, but I 
think the result would be very similar.  Not giving away the answer in 
case folks want to give it a try--or remember the same article. ;)

--Crow
/**/

On 4/9/2014 2:01 PM, Andre Majorel wrote:
> On 2014-04-09 16:26 +0100, Neil Johnson wrote:
>
>> Just watching this video of Barrie:
>>
>> https://www.youtube.com/watch?v=sATM6gi7bn8
>>
>> Look at the slides carefully -- especially the background image.
>> Great sense of humour :)
> That's from http://xkcd.com/730/
>
> The AD639 transfer function at 41:19 looks like it would make a
> good wave shaper.
>