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Herbert 1701 Species B Generations 2 & 3

As noted with the release of Herbert 1701 Species B Gen 1, species B is an improvement over species A in the area of efficiency. A good chunk of this improvement is in the form of the MAX8212 Solar Engine versus the previous Miller SE, but you might have also noticed a difference in the transistors used in the B species. The difference was a move from the previous 2N3904 (and not seen but complimentary 2N3906) bipolar junction transistors to 2N2222 and 2N2907 BJTs (the 2N2222 you will see in the schematics below). A small upgrade, but it fell inline with an evolutionary move to a more efficient species.

If your eyes glazed over reading the last paragraph, don't worry, mine did too. I had to mention it for the sake of full disclosure on this project. And now we can move on. No wait. I'm sorry. A quick note on the difference between PNP & NPN transistors (2N2907 is PNP, 2N3904 is NPN). I'll skip the really boring stuff and just say the major differences are that PNP turns on with a low voltage (ground or -) to its base and allows current to flow across it to a load (the LEDs); the NPN is opposite, turning on with a positive voltage (current really) and allows current to dump out of a load and pass through it to ground. The reason this is important is that one device moves holes (PNP), the other moves electrons (NPN); and electrons move faster. So we like NPN. There, done.

The reason I mentioned all this is in order to keep species B as a more efficient critter than species A, we want to switch back to using NPN transistors. The problem is that the MAX8212 outputs a low signal when it is active, and as I just mentioned PNP turns on from a low signal. Thus a PNP transistor is needed, but there is hope because the PNP transistor dumps out a positive voltage, which we can use to turn on NPN transistors. And that is a good thing.

Here we have exactly that in the form of Herbert 1701 Species A Generation 1A. The poor little guy is not exactly a remarkable change in generations, so rather than a full jump ahead, it gets a letter added. Good stuffs, except it isn't.

Rather than the nice efficient energy usage of Gen 1, this Herbert behaves much in the same way as Species A. That is to say the LED flashes as Herbert charges and discharges the capacitor. The LED flashing is Herbert's way of telling us that it has used up all his energy and has to rest for a moment. Not quite the spritely little Herbert that it once was. So where did the energy go?

The answer is in more glazed eye stuff: Across the base to emitter junction of the 2N2222. The current flow to the base straight off the 2N2907 is just too high compared to the current flow across the LED to the collector, and so all that extra juice dumps straight to ground; leaving Herbert feeling empty and lethargic. Poor poor Herbert. No one to talk to, play with, or be with.

Hope is restored to the B species in the form of a couple extra resistors. The 10K/1M resistor combination that Herbert 1701 Species B Generation 2 developed drops the current at the 2N2222 base to a more reasonable level, keeping Herbert chock full of electrons to keep that LED glowing bright. Herbert with your LED so bright, won't you guide my sleigh tonight. Then how the Herbert's loved him. Sorry.

Herbert 1701 Species B Generation 3 follows in Species A's footsteps, although perhaps "light path" would be a better term. Two cells pumping out light where before there once was one. The difference is that this species continues to maintain enough energy to keep both "cells" illuminated without problem.



While not the greatest leaps in evolution, these are building blocks that will allow Herbert 1701 to continue on a path towards... well towards something else. And that is what evolution is all about. Next up, we will determine which came first; the chicken or the egg. Won't that be fun?

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