Slide Rules, Electronics Studies

published 2025-11-10

By Christopher Howard

I'm continuing, as spare time allows, to work through electronics practice problems in some various electronics lesson books and handbooks I have access to. I'm finding the most satisfying way of learning is to work through the practice problems, working through the mathematics with a slide rule close at hand.

I am also working on exploring more of the scales on my Pickett N-16-ES, which was designed for electronics applications. I was a bit confused at first by the TH, SH1, and SH2 scales, but eventually figured out that they are for hyperbolic trig functions. Not having an application for those at the moment, I moved on. As far as the main scales go (C, D, etc.) the N-16-ES is mostly similar to the other slide rules I have, except that there is no inverted folding scale (CIF).

As far as regular trig scales, the N-16-ES is similar to the others, except that they are all inverted, i.e., go from right to left instead of left to right. I found that, to complete my usual trig problems, I need to flip the operation, say, rearrange it from a division problem into a multiplication problem.

I learned how to use the reactance calculator scales on the back, working through some problems of calculating impedance for various frequency and capacitance values. It seems debatable whether using these scales are really faster than just using the regular scales, which would involve just one multiplication for the f x C, then another for 2 x pi — that could be marked onto your slide rule — and then getting the reading off the inverted scale, or not, depending on whether it is a capacitive or inductive reactance. But I think using the specialize scales is a little easier to keep track of mentally, and of course you have your other scales for wavelength or angular velocity which can be used instead of frequency, when needed, without having to modify your basic procedure. The N-16-ES also has a system of tick marks which can be used to help you calculate the decimal place, rather than doing the addition or subtraction of the exponents in your head, for the range of common electronics units (mF, uF, pF, kc, mc, etc.)

The main annoyance with these reactance scales is, in the standard procedure, sometimes the C or L value you want ends up being off past the end of the bridge, so you have to rewrite that value slightly to get it back in — e.g., change 0.56 pF into 5.6 x 10^-13. This scale is not a standard scale, going from 1 to 10, but rather goes over two orders of magnitude, 0.1 to 10, so things work a little differently.

There are some other things I wanted to write about, like my astronomy studies, but I've run out of time in the lunch break. Hope to be posting again soon.

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CC BY-SA 4.0 Deed