User:Glrx/sandbox

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Unicode NFC and article titles

  • Should Horatio Nelſon be blue and link to Horatio Nelson?
    • Nelson Nel%C5%BFon Nel%25%26%23x17F%3Bon
  • Führer (composed) versus Führer (decomposed); apparently not a redirect; the links were normalized.
    • F%C3%BChrer Fu%EF%BF%BD%3Fhrer Fu%26%23x308%3Bhrer

Flag Books

Power supply voltages

Analog

  • ±15 (early transistor and opamp; 40V transistors)
  • ±12
  • ±5
  • +5

Logic

  • ±?? ±?? (1401)
  • +3.6 (integrated RTL; I think it was 3.6V; funded by satellite needs and power supply = 3 NiCd)
  • CosMOS (RC) 3-15V
  • +5 TTL; 0.8 to 2.8V; pullup not strong;
  • -5.2V MECL. Negative supply so NPN transistors and ground ref. Why 5.2 and not 5.0?
  • 3.3V CMOS discrete; any bipolar?; goal to lower power consumption; keep 2.8V? 5*.707 3.535V.
  • 2.0V
  • 1.8V
  • 1.5V
  • 1.2V
  • 1.0V

Significant transistors

  • CK722 Raytheon. Ge PNP. One of the first plastic?
  • 2N696 and 2N697 Si NPN mesa; no epi; before thick oxide known as a diffusion shield. BTL made silicon; somebody had Ge mesa. I think mesa etch was to reduce C_bc. Did etch have an advantage with exposed basecollector junction? Why not make smaller die? I think PIN and Snap diodes want uniform field, so they have junctions exposed by dicing.
  • 2N1304 and 2N1306 Ge NPN/PNP. Typical switch. Which transistor types used on 1401 (033 / 034)? IBM document had a list.
  • what was the typical Ge power transistor? 2N176?
  • 2N2222 Si NPN epi planar annular
  • 2N3055 Si NPN power. Original was hometaxial, but later copies went to epitaxial. Hometaxial is single diffusion: https://encyclopedia2.thefreedictionary.com/hometaxial-base+transistor OMG, http://powersupply.blogs.keysight.com/2012/09/early-power-transistor-evolution-part-2.html describes having the wafer be the base, simultaneous diffusion of collector on one side and emitter on the other, then an emitter-side mesa etch down to the base. With the base exposed, a base connection could be made. Why fancy emitter geometry?
  • 2N3904 and 2N3906 Si NPN/PNP.
  • 2N5109 and 2N5160

RCA Power Transistor Applications Manual (1983) has descriptions hometaxial, etc.

Cross-evaporation: US 3709695, Bowman, R., "Fabrication of Semiconductor Devices", issued 1973-01-09, assigned to Motorola

Costas loop

The Costas loop article needs work. See Talk:Costas loop.

The angle addition formulas:

We can use those formulas to find the result of a phase shift.

Angle addition formulas taken together produce the heterodyne formulas:

These clarify the first image in the article that has a simple story of in phase and quadrature. The diagram uses a sin() phase carrier and a sin() phase VCO.

The image does not give the heterodyne formulas, but the image shows a zero phase difference between the carrier and VCO because both are described as . To model the phase difference, let a be the carrier phase and b the VCO phase. The upper and lower branches then produce:

The summed phases get filtered out. Demodulation is on the upper branch: cos(a-b) is approximately cos(0) = 1. Phase control on the lower branch. The lock point is stable at near zero phase difference: if b gets a little ahead of a, then sin(a-b) is negative which will reduce the VCO phase.

This diagram started the article, has the cleanest math, and the rest of the article should follow suit. Top branch should be demodulation and bottom branch phase control. The phases going to the mixers should be sin() and cos().

In contrast, the two diagrams in the final section of the article are confused, inconsistent, and changing.

The recent formulas given in the diagrams for the lower branches are:

We should get the lower formula by substituting for , but that gives

Notice the -θs; that makes the lock point stable for small values. This last formula is identical to the cos case.

In other words, the formulas says the first diagram locks with a phase difference near 0, and the second diagram locks with a phase near 180°.

If we look at earlier versions of the two diagrams, the situation is still confused. The "before sync" SVG file from 2012 recognizes that the -90° phase shifter creates a minus cosine, so it negates m(t). That makes the loop unstable for small phase differences between the carrier and the VCO. The "after sync" SVG from 2012 is even more confused. It assumes the phase difference between the VCO's sin() and the carrier's sin() is zero. That is evidenced by the sin(0) expression in the lower branch. It expects the top branch to provide the demodulated m(t), so it is trying to mimic the diagram in the first section. It does not show the phase error, so we cannot comment on stability.

The same issues are present in another diagram:

The expressions for the upper and lower branches with a 90° phase shift to the lower branch should be (with a the carrier phase and b the VCO phase):

And -sin(-x) = sin(x) by antisymmetry, so the "after lock" lower branch formula is correct, but the lock is unstable as shown. IF the VCO is a little fast, then the phase difference with be positive, and the feedback will speed up the VCO even more. The diagram is wrong (assuming positive filter gain).

Amelia Earhart

Stable merge

Mark 14 torpedo

Battle of the Atlantic

Enigma

Various contact protection articles

Audion

Poulsen arc

Glow discharge simulation

Gas discharge tube

Arcing

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