Building with Transistors

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I have developed a number of linear IC designs for electronic music since the 1970s. Since about 2000 though, through circuit design and implementation, my knowledge of discrete transistor designs and what can be done with them has increased a lot.

A lot of insights have come from these discrete transistor designs:

  1. The key to magical electronic sound is to prefer some circuit imperfections over others.
  2. You can make anything with transistors.
  3. Feedback cures many ills.
  4. Look into the current mirror.
  5. It's easier to tune 16 filters than 16 oscillators.
  6. One good Schmitt Trigger does more than a precision voltage reference, two voltage comparators and a flip-flop.
  7. For every Vbe an equal and opposite one can be found.
  8. Circuit design as Topology is a different way of looking at things.
  9. Complementary symmetry designs are tremendously useful.
  10. More generally, having a wider diversity of component types (example: precision resistors) yields synergies not possible with ICs.
  11. Tuning is relative, preferring ratios more than absolutes.
  12. Elegant circuits seem to have fewer components for a reason.

I find it possible to now build discrete transistor circuits which can do more with less than an IC op amp. In numerous cases discrete transistors offer much higher performance than ICs. For example, in areas such as bandwidth, phase delay, and available current drive.

The price paid for all of this flexibility and performance compared with ICs is of course more circuit board area, somewhat more total components, and in most cases also higher power. But this does not mean unaffordability, nor is discrete circuit implementation impractical.

PCB layout with discrete components is simpler than as for ICs, because most of the components are similarly sized with respect to each other. Components can be placed for favorable connectivity, versus extra PCB traces or vias needed to reach specific signal pins. Signal and power integrity are easier to maintain because there are no on-chip/off-chip power connections that represent off-board impedance discontinuities or potential resonances needing specific forms of power supply decoupling.

Transistors make me happy because direct access to these little crystals is just plain creative fun, an art form like painting. 


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