How to design a Schmitt trigger with specified threshold voltages, using two npn transistors.
Hot transistors fail early. Keep junction temperature down by moving the heat away, like this.
What valves are, how they work, why there are different kinds, and how they are (or were) used as amplifiers.
Understand and design resistor capacitor networks that meet specifications, including how to make low pass and notch filters.
How capacitors charge, plus the meaning and use of the idea of 'time constant'.
Sin, cos, tan, log, ln, e, binomial, RMS, stray C, energy storage, complex numbers, arith. & geom. progressions, etc.
Ordinary BT local-line telephone cable has low attenuation even at 100 kHz.
The Telephone No.332 was the first GPO telephone with a bell. It had an ingenious anti-sidetone line-matching circuit.
Circuit diagrams and operation of the C.B.S. 2 manual exchange system.
Philipp Reis made a working telephone in 1860 - long before Alexander Graham Bell - from a knitting needle and a cigar box.
In 1934, the Postmaster General decided that evening trunk calls should cost a shilling. The result could have been predicted ...
What it is, and how Millikan measured the charge on an electron using a stopwatch.
The electric field, flux, potential, what a capacitor is, what it looks like, and how you make one.
If a capacitor can hold a joule of energy, how much energy does the same size battery hold?
Inductance, magnetic fields, and how they are used to store energy.
The physics and engineering behind the plumbing of a house water supply system, and how to design a system.
How it works, and how it was used with Britain's Chain Home wartime radar defence network against night bombing.
During the Napoleonic wars the major French cities were linked together by a huge network of semaphore signalling stations.
A windmill sail looks like a garden trellis, not an an aircraft's wing - so how does the wind make the sails rotate?
The user manual for the suitcase radio designed by SOE for British agents in WW2.
The process of designing a product to meet the user's needs is not always straightforward.