I got a Roomba robovac a few months ago, partly because I hate vacuuming, partly because I grew up in the 1960s, when we would have vacations on Mars by 2025, and robot maids and butlers would take care of us.

I rebuilt my original astable multivibrator with the 2N3904, transistors, better matched capacitors and 10K and 68K Ω resistors from the improved astable multivibrator I wanted to see if that made a difference in the original circuit’s behavior.

My theory about email spammers.

Everybody who’s had kids knows that they love trains. I’ve visited the Colorado Railroad Museum and the Forney Transportation Museum several times because of kids. Both museums have a variety of steam locomotives. The Forney has a partially restored Union Pacific Big Boy.

I ended up wanting to know how locomotives worked, and why they look the way they do. Unfortunately, the emphasis at museums is always on how cool steam locomotives are, or the “gee whiz” factor. None of the museum gift shop books seemed to have this sort of content, tending more towards the stamp collecting aspects (4-8-8-4!).

My lovely wife gave me a book, How Steam Locomotives Really Work by P. W. B. Semmens and A. J. Goldfinch as a present.

I’ve been on jury duty 3 times, once spring of 1988, another time in 2016, and my favorite, Monday, February 25, 2002.

Here’s an incredible cover of Steely Dan’s My Old School, the enigmatic jazz/rock song from 1973. Happy 50th.

For some reason this winter, I’ve wanted some experiences from my past just one more time.

I built an “improved” astable multivibrator circuit from:

IMPROVED ASTABLE MULTIVIBRATOR, by RAJU BADDI, National Center for Radio Astrophysics, TIFR, Ganeshkhind P.O Bag 3, Pune University Campus, PUNE 411007, Maharashtra, INDIA; baddi@ncra.tifr.res.in

Here’s the schematic of the improved circuit:

Original astable multivibrator post.

I built an astable multivibrator from discrete components:

I used 2N2222 transistors instead of BCS547.