98
votes
Accepted
How were schematics drawn before CAD?
Historical Context
I was trained at Tektronix to be an electronics draftsman.
Tektronix provided classes for anyone interested. It's quite similar to drafting for construction. You had the usual ...
- 78.8k
58
votes
How did 455 kHz end up being a commonly used IF (intermediate frequency)?
Piecing together information from a number of sources on the web, I believe this is the correct combination of circumstances:
Early amplifiers were not stable much above 500 kHz, so the IF had to be ...
- 178k
49
votes
How did people realize they could do logic with electronics?
From the Wikipedia article, Boolean algebra:
In the 1930s, while studying switching circuits, Claude Shannon observed that one could also apply the rules of Boole's algebra in this setting, and he ...
- 134k
47
votes
Why are the E-series numbers different from the powers of 10?
I've really enjoyed your question and definitely upped it. Your question made me think about and do some additional reading on the topic. And I really appreciate what I've learned from the process and ...
- 78.8k
46
votes
Accepted
How did scientists deal with electronics' problems before Kirchhoff and Ohm's laws?
This is a bit like asking how Aztecs built cars without the wheel: they didn't.
There was a chain of invention by scientists in the early 1800s building off each others work. Prior to then there was ...
- 47.1k
40
votes
How did old WW2-era radars accurately measure time delay and integrate this into an oscilloscope?
The basic PPI (plan position indicator) radar display — the kind that has a bright line that sweeps around a circular screen like the second hand on a clock — works on the principle that ...
- 178k
35
votes
How were schematics drawn before CAD?
In my first job in 1975 at Bristol Aerospace (now Magellan) we had a good aviation and NASA qualified draftsmen, but one kept making D and E size drawings so microfiche would not create false dots ...
- 148k
35
votes
Accepted
How were four wires replaced with two wires in early telephones?
How was this possible? Wouldn't the current from microphone affect
speaker on the same side?
The modern telephone is wired in a Wheatstone bridge arrangement like this: -
So, if you ensure that the ...
- 473k
34
votes
How did people realize they could do logic with electronics?
As with so many other important developments in logic and computer science, it was almost certainly the mathematician and philosopher Charles Sanders Peirce, whose work predated Shannon's by decades:
...
- 440
33
votes
Why are chip designers called "triangle pushers"?
They are called "polygon pushers".
polygon pusher: n.
A chip designer who spends most of his or her time at the physical layout level (which requires drawing lots of multi-colored polygons). ...
- 8,275
33
votes
Accepted
Is there any reason why 5 volts is so ubiquitous for powering small consumer electronics?
While the original call for 5V was doubtlessly for TTL (as mentioned in the comments, specifically the reverse-biased BE junctions of bipolar transistors which are almost ubiquitously rated for 6V), ...
- 5,497
28
votes
How were four wires replaced with two wires in early telephones?
Remember that the telephone was invented over 30 years before the triode vacuum tube, and over 70 years before the transistor. Changing, combining, and subtracting audio had to be done with resistors,...
- 23.2k
28
votes
Is it correct that in a hard disk both surfaces of each disk are capable of storing data?
I worked on every major disk drive manufacturer of HDD’s including our own at Burroughs for 11 yrs starting in ‘83
All 14” and 8” Head-Disk-Assemblies (HDA) used the top surface for servo feedback and ...
- 148k
27
votes
Accepted
Why are chip designers called "triangle pushers"?
Early masks for the creation of layers on an IC were created by a photographic process that involved exposing the original photographic plate through a mechanically controlled triangular aperture. ...
- 10.1k
21
votes
Why don't ICs include bypass capacitors?
The bypass capacitances on the order of 0.1uF are too large for silicon processes used for creating ICs. Metal-oxide-semiconductor (MOS) structures are used to create capacitors inside the ICs. ...
- 38.6k
21
votes
Accepted
Why don't ICs include bypass capacitors?
The last time I got a quote to add capacitors or resistors to a chip it was about $0.01 per part to be added plus the cost of the part. Parts like say an Intel/Altera/Xilinx FPGA, or a processor ...
21
votes
Accepted
Why are the outputs of these gates tied together in the Apollo Guidance Computer?
RTL logic is open-collector, which allows the wire-OR connection (in this case, more precisely, wire-NOR.) The characteristic of wire-OR is that gates only drive low, so even if more than one is ...
- 58.6k
20
votes
Accepted
Why does `buck` mean `step-down`?
It's the same sense as to "buck" a trend:
to oppose or resist (something that seems oppressive or inevitable).
"the shares bucked the market trend"
synonyms: resist, oppose, contradict, defy, fight ...
- 24.7k
19
votes
Was the Intel 186 chip commonly used anywhere? Was it only found in industrial computers? Why not PCs?
There was an actual PC (somewhat compatible) computer built with the 80186.
That was the Tandy 2000 from Radio Shack.
I have vague memories of being envious of the better graphics it had over the ...
- 73.6k
16
votes
Is there any reason why 5 volts is so ubiquitous for powering small consumer electronics?
One of the reasons was that the European Commission facilitated an agreement among major handset manufacturers to adopt a common charger on the basis of the micro-USB connector for data-enabled mobile ...
- 10.9k
15
votes
What is the actual niche for "operational amplifiers" these days?
Here are some applications I've seen in the past year just off the top of my head:
Current sense amplifiers, A/D input buffering, active filtering, DAC output buffering, transimpedance amplifiers for ...
- 24.7k
15
votes
Accepted
How did people make oscillators before they had the triode?
Three-terminal devices aren't the only way to produce amplification, and therefore sustained oscillation. It's actually possible to build free-running oscillators (and even amplifiers) using only two-...
- 20.6k
14
votes
Was the Intel 186 chip commonly used anywhere? Was it only found in industrial computers? Why not PCs?
The 80186/80188 is not a plain microprocessor but a microcontroller as it integrates some peripherals like timers, interrupt controllers and DMA controllers into it.
Compared to an IBM PC which had ...
- 172k
14
votes
When is it appropriate to mix 74LSxx components with original TTL 74xx?
One potential problem with substituting LS for regular TTL is the reduced fanout.
Regular TTL can typically drive 10 TTL loads. LS TTL can typically drive 5 TTL loads (8 mA). I use 'typically' here to ...
13
votes
Accepted
Why does wire gauge go down as the physical wire size goes up?
A seminal empirical definition of wire gauge was the number of times the wire had been passed through a draw plate. Each draw plate would reduce the diameter of the wire by about 10%, therefore the ...
13
votes
Accepted
How do I get more clarity on the meaning of "integration" in VLSI?
You’re overthinking this. An ‘integrated circuit’ (IC) just means a device that has more than one active element (diode, FET or BJT) implemented on a single die. That’s it.
The IC is differentiated ...
- 58.6k
12
votes
How low have mains frequencies gone? What areas once used 30 Hz, and why?
The historical reasons for using 30 Hz and other frequencies is documented in the book Electrical Engineering Papers by Benjamin G. Lamme, published in 1919. In the article 'Story of the Frequencies' ...
- 57k
12
votes
Why were bipolar junction transistors (BJTs) better than metal oxide semiconductor field effect transistors (MOSFETs) in the past?
Bipolar transistors had a head start of about ten years over MOSFETs so they were adopted first. They were, and remain today, somewhat less expensive than MOS to manufacture, at least for discretes, ...
- 58.6k
Only top scored, non community-wiki answers of a minimum length are eligible