This 17 minute film provides a good but simplified description of the state of the art at the start of World War II.
-- The description of how a signal gets to the input coil of a receiver is quite good. Imagine if that coil had no good ground, and no counterpoise. We see the importance of the counterpoise in this video: https://soldersmoke.blogspot.com/2023/03/an-antenna-for-high-school-direct.html
-- I like the repeated demonstration of the reality of envelope detection. Too often people have bought into the idea that envelope detection is not real, and that some form of mixing using the carrier in lieu of the local oscillator is what is really happening. That is just not true. Envelope detection as described in this film is real.
-- The description of mixing is very simplistic. They describe the generation of the difference product, but not the sum. But hey, the film is only 17 minutes long! It takes a lot longer than that to fully describe mixing (ask me how I know!).
-- At the very end, there is a shout-out to the BC-348. FB.
I like their animated schematics. Good visualization. Some of the thermionic devices (ahem!) are tilted in the same direction of signal flow to help the viewer understand circuit operation. Should we be drawing our schematics with that tilt? Bill and Dean, do you need to redraw the Soldersmoke DCR schematic?
ReplyDeleteInteresting Time Capsule!
Mike: Although the tilting in the 1942 thermatron schematics might have been useful, in the case of the 2026 solid-state DC receiver, I think this would be more of a matter of "tilting against windmills" (thank you Cervantes). So no, we (I mean Dean) will NOT be redrawing the schematics. 73 Bill N2CQR
ReplyDeleteOk, no tilted schematic symbols. Signal flow(s) get more complex in the Soldersmoke DCR, especially in the product detector.
ReplyDeleteYes, but Alan Wolke W2AEW explains it all perfectly here: https://www.youtube.com/watch?v=junuEwmQVQ8 Discussion of the signal flow starts at around 5:15. NO TILTING REQUIRED! 73 Bill N2CQR
DeleteW2AEW does explain it all! He does great videos.
DeleteI was working on a pulse-counting FM detector when I found his video. What he detailed in the video was happening on my bench, all in the same way.
Not bad for 17 min. It is funny how some of the thermatron diagrams were tilted to the right as though the "radio wave" was a physical wave smashing into the poor thermatrons. LOL.
ReplyDelete