

Show HN: SevenFortyFun, a transistor level op amp kit - OpenAnalog
https://www.github.com/OpenAnalog/SevenFortyFun

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kazinator
Hmm. That Q8/Q9 current source being duplicated into two mirrors in separate
stages (Q17/Q18 and Q19/Q20) seems quite pointless in a discrete amplifier. In
a realistic discrete amplifier, even if you still used the two mirrors, you'd
program them separately with just a resistor. The two stages do not require
identical currents. I suspect this usage has to do with what's easier to
fabricate on silicon.

In the VBE multiplier around Q16, I would add a potentiometer to adjust the
quiescent through the output stage, even though the `41 of course has no such
thing.

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fernly
So I can't figure out why this product should exist (as a product, vs. a lab
exercise). On the KS page it only mentions "You can finally get the chance to
understand whats going on inside those ICs!" Which is worthwhile, I suppose,
to a minority of hardware designers, just as learning assembly language is
worthwhile to a minority of programmers. But does that translate into a
business plan? What is the market for such kits?

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turnip1979
I don't understand why they need kickstarter funds to test if the board works.
I thought there are services out there that print one off circuit boards for
reasonable amounts.

