Handy reactance calculator

[Doug Coulter]

I've been using a copy of this WWII era slide rule for gosh, more or less my entire career. It's not to the nth decimal place, but it's good to get in range for various problems. The original is pretty much toast, but luckily in the 70's I made a photocopy and kept that so I can make fresh ones. Even the copy is getting old now, but here are images of the two sides so you can print them and make your own. It's a big time saver for a lot of problems. Then and now, truly precision inductors and capacitors weren't common, so the acuracy is still good enough to get you to the point of just needing fine tuning. Also good for R-L and R-C filter types of problems, which is why there are two sides.

You should be able to right-click these images and save them for your use, I kind of doubt Shure cares anymore (heck, they were free then).

To make one, I use some cardboard, like from the back of a writing pad, to glue the printed paper to. The insert you simply glue, and trim the result to size. The outer pieces you have to make the cutouts in, and add another layer with a larger cutout to allow the insert to fit. I then just stable the outer pieces together.

I've had (and written) computer tools to do this, but actually, this is faster and easier when looking over trade-offs than typing into one.

[Starfire]

You're showing your age Doug

[Doug Coulter]

And my bad habits, guess what that brown stain is (hint, don't leave your slide rule over the ashtray). I thought my picture gave the age away!

[Starfire]

Sliderules are not much used nowadays but they are still useful if you have the skills and the lights go out and you dont have a UPS backup. I grew up with them too

[Doug Coulter]

Well, I have the good old slipstick type too, the general purpose one -- I won't say I'm real facile with it compared to a good hand calculator. This one just has these particular equations "built in" so it's a lot simpler than those to use, but of course, only solves this one problem space. We have some people here who are just learning about reactance, so it's good for them, as it was for me when I was just learning. And heck, it's still handy now!