1930s mechanical TV

[rld-tv01]

Recently I won a couple of eBay auctions from two different sellers. First was letters between a TV experimenter (Ray Wolf) and Don Lee Television studios and Iowa University TV studio. The second was between tv experimenter (M J Maynard) and Television Magazine. It was interesting that Television Magazine told Mr Maynard his article for making a mechanical TV motor was two complicated because you needed a lathe to make the motor parts. Maynard kept the rejection letter and a copy of his article where it ended up on eBay 40 years later. So I'm attaching a copy of Mr. Maynard's schematic here on the television karma site.

[M3-SRT8]

Interesting footnote to TV History.

Of course, around this time (earlier, perhaps?) wasn't Philo Farnsworth up tp speed with his Electronic TV? It would appear these guys were a little behind the curve with their mechanical approach.

LJB

[rld-tv01]

See http://www.earlytelevision.org/w9xk_history.html for history on transnission transmission at Iowa University and when they changed to electronic transmission. Even though electronic Television was under development in 1933 no one was transmitting. Mechanical television was only transmitting a couple of hours a day. Television news had an article on using a 3 inch Western Electric CRT for television in 1933 but the article was only on the CRT and not much on the supporting electronics required to receive a signal over the air. These guys were television hobbiest building a receiver at home and not television manufactors. Also Don Lee in Los Angeles later broadcast Electronic television a few years later.

[David Roper]

There were periodic "broadcasts" (in the sense that over-the-air transmission was used) of all-electronic TV in the early 1930s, the best documented of which were the RCA field tests of 1932 (180 line) and 1933 (240 line). But of course only RCA engineers had sets to receive them.

[Steve McVoy]

M3-SRT8 is correct that most mechanical stations had stopped broadcasting by 1933. The novelty was gone, the depression was in full force, and the picture quality of mechanical TV made entertainment broadcasts impossible.

But electronic TV wasn't ready. Philo's image dissector wasn't sensitive enough, and the iconoscope was crude. RCA used a mechanical camera for their 120 line tests in 1934, and it wasn't until the end of 1935 that RCA's electronic camera was good enough to use in field trials starting in 1936.

[David Roper]

Originally Posted by Steve McVoy

. RCA used a mechanical camera for their 120 line tests in 1934, and it wasn't until the end of 1935 that RCA's electronic camera was good enough to use in field trials starting in 1936.

RCA didn't use a flying-spot camera (120 lines) after 1931. The 1934 tests were not the first using an iconoscope camera and were in fact 240 line.

http://earlytelevision.org/rca_1932.html

[Steve McVoy]

I should have looked at my own website before I replied. David, you are right, of course.

[Hawkwind]

Here's a page from an old book I have about a Scanning Disc TV kit from 1928:

http://s24.photobucket.com/albums/c4...sc_TV-1928.jpg