"Bridge Rectifiers" 1969 USAF Electronics Training Film

[Homer J Simpson]

[rbm]

Weird.  The narrator refers to the diode's anode as collector and cathode as emitter.  Those would be transistor pin references in my book but maybe the US military have difference nomenclature.  The other weird thing was the current flows; they were shown opposite to what I learnt.  That is, current flows in the direction pointed to by the anode.  Again maybe another US military nomenclature.

[Brumby]

It may seem weird these days - but I can see how it would have been less so back then...

We are talking about 1969 - when a lot of valve (tube) gear was common.  With valves, you get to consider electron flow to understand the operation - something technicians would need to know.  Since this video was aimed at such an audience, it would seem appropriate to maintain that convention.

Labelling the ends as Collector and Emitter is a little curious - but I can only think they were trying to introduce these new terms to differentiate valve and solid state components.

The thing I noticed more was that they made no reference to the forward voltage drop of the diodes - and in fact directly referred to them as a short circuit in the forward direction at one point.  The clue as to why I believe they did that lies in the fact that they were talking about power supplies in the 300-500V range - typical for valve circuitry.  In that range, the V_f of a semiconductor diode isn't going to matter a whole lot.  (But it is still wrong.)

[retrolefty]

Weird.  The narrator refers to the diode's anode as collector and cathode as emitter.  Those would be transistor pin references in my book but maybe the US military have difference nomenclature.  The other weird thing was the current flows; they were shown opposite to what I learnt.  That is, current flows in the direction pointed to by the anode.  Again maybe another US military nomenclature.

 When I went through USAF electronics in '66 they made a point in the beginning that they would teach
"electron current flow" Vs "conventional current flow". They didn't really explain why. The military did lots of things that they didn't explain well.   

[LaserSteve]

That must be a contractor made training video. It just does not fit the classic USAF format. I've seen the tube style notation before, though.

Steve

[T3sl4co1l]

Mil also followed electron current flow for a long time -- woe be unto you if you're reading a schematic and not realizing why negative voltage is coming out of the arrow direction from a diode!

Tim

[BrianHG]

  THAT MUSIC     

[Brumby]

Enjoy!

(Bonus if you like trains...)

[grifftech]

Just posting so I can find this on my computer

[floobydust]

Where's the selenium?

[Neomys Sapiens]

Don't ask - use your nose!
Those things are the source of a terrible pun in german EE slang:
'Rectifier' is 'Gleichrichter' in German, for those made of Selenium, it was explained as coming from 'Gleich riecht er' = 'soon it smells'!

[floobydust]

I thought the training film might be talking about selenium rectifiers, their use apparently fading out in the 1960's but 11:47 shows a microwave detector cartridge diode like a 1N21B? The Training Board seems to have normal DO-204 kind of parts on it.

It was a "big stink" USAF using selenium rectifiers on aircraft 1957, if poisonous smoke etc. in B-52's.
Good riddance to the worst semiconductor ever.