[sdiy] Triple Lockhart cascade (while we're on the subject of waveshaping...)

[Dan Snazelle]

1.2 volts peak to peak?


> I picked the 30K/10K ratios of the first two inverting op amp stages
> to get a gain of 3; Ken's website said the Lockhart folder wants a +/-
> 1.2V signal and gives out a +/- 0.4 V signal. That's how I got the
> number of 3. I boosted the feedback resistor of the last stage by 5 so
> it would look more like a usable output signal, but I don't show the
> output of that (it's just a gain).
>
> I didn't get what I expected. One Lockhart stage gives one fold. But
> two gives four, and three gives... whoa, 13!!! How is that happening?
>
> Someone wanna breadboard this up and tell me how it sounds? :)
>
> Here's the LT Spice file if anyone wants to play around with it:
>
> users.ece.gatech.edu/~lanterma/lockhart3.asc
>
> - Aaron
>
> P.S. I found that the Lockhart stage needs to see that 10K impedance
> at the output of the transistor stage to work right. If you don't
> include it, and you have it feeding infinite impedance, then the
> wavefold happens essentially instantly once you get to either side of
> ground.
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