Before YouTube, you had to watch your educational videos on film. In the 1970s, if you studied radio, you might have seen the video from Universal Education and Visual Arts, titled Understanding Electronics Basic Radio Circuitry. The video’s been restored, and it appears on the [CHAP] YouTube channel.
The video starts with a good history lesson that even covers Fessenden, which you rarely hear about. The video is full of old components that you may or may not remember, depending on your age. There’s a classic crystal radio at the start and it quickly moves to active receivers. There’s probably nothing in here you don’t already know. On the other hand, radios work about the same today as they did in the 1970s, unless you count software-defined varieties.
We expect this was produced for the “trade school” market or, maybe, a super advanced high school shop class. There were more in the series, apparently, including ones on vacuum tubes, the transistor, and the principles of television.
We were sad that the credits don’t mention the narrator. He sounded familiar. Maybe Robert Vaughn? Maybe not. A little research indicates the company was a division of Universal Studios, although the Library of Congress says it was actually produced by Moreland-Latchford Productions in Toronto.
Maybe these videos were the next step in becoming a child radio engineer. If you like old radio videos, this one is even older.
Sounds like Alex Trebek, who was Canadian, so…
I liked the one tube ‘breadboard’ circuit (2:53) – a piece of wood with nails for tie points.
Hey, that’s why it’s called a breadboard after all. Originally it was quite literally a wooden cutting board with nails and components stuck on top. I bet varying humidity in the wood would create all sorts of fun parasitic capacitance to figure out…
All of the graphics in this video ooze style by the way, I like what they were able to accomplish with just printouts on colored construction paper.
Where I live we use uncoated thumbtacks on plywood boards instead.
They’re making for good solder points, too.
Takes me decades back when studying electronics in Toronto at Radio College of Canada. Television was included as we were receiving Telecasts from Buffalo and Rochester. There was none in Canada until 1952. Montreal was first then Toronto. So I have seen A.M then F.M. then Side band. Also high fi came along. Stereo showed up.Color T.V. .computers satellite G.P.S. cell phones. Micro wave towers . That’s just a few items that I was privileged to experience. Am still active in the field of electronics at my present age of 94. Upon reflection, am astonished at the advances made during my lifetime. From Crystal radio to space flight to DNA to defeat of Polio .
The video is fine, but makes it more complicated than it really is.
It does so, in order to group everything into function blocks, I think.
As if someone was going to build an overly complex superhet receiver..
In practice, though, a single tube was sufficient for building a TRF receiver.
(By 1970s, there also were even more miniature battery tubes with wires,
so a complete AM receiver did fit in a matchbox; for matches, not a tuner.)
It doesn’t need much parts to build a basic audion, for example.
Or his cousin, a regenerative receiver (audion w/ backfeed; an ultra audion?).
Which was followed by super-regenerative receiver (a pendulum audion).
(It was used as receiver in basic CB walkie-talkies at some point, I think, due to simplicity.)
A crystal radio with a tube for an RF or AF amp was a possibility, too.
There were so many variations of that. It was a whole sub hobby of its own!
The tube was involved in RF amplificiation/detection/AF amplification or all of them.
https://en.wikipedia.org/wiki/Tuned_radio_frequency_receiver
https://de.wikipedia.org/wiki/Einkreiser
https://simple.wikipedia.org/wiki/Audion
https://en.wikipedia.org/wiki/Regenerative_circuit
https://en.wikipedia.org/wiki/Superheterodyne_receiver
Certainly does sound like Alex Trebeck in his younger days.
Brings back memories of electronics shop class in high school.
We had breadboarding systems like that.
My HS ‘electronics’ class (1972) consisted largely of building an “All American Five”, five-tube AM radio. Learned a lot about tubes and how they worked, not much about anything else. Still, building the radio was fun. Listing the tubes was almost a litany: 50C5, 35W4, 12BA6, 12BE6, and one I can no longer remember…
One thing I learned: do NOT have the radio plugged in and switched on when pointing out to little brother the functions of the pins on the rectifier. Discovered that line voltage causes a rather loud and uncomfortable hum in the brain/nerves….
12AV6 or 12AT6 is the missing tube, as detector and first audio amplifier (and maybe part of the AGC circuit, my rusty mind is nagging).
Yes, that’s the later AA5 set, made with 7-pin miniatures. Before that, starting about WWII, it was usually 12SA7, 12SK7, 12SQ7, 50L6, and 35Z5 octal tubes. FM receivers usually had something like a 6/12DT8 for their discriminator and oscillator, IIRC.