Monday, January 25, 2021
Erla
Speaking of radio and 1925, here's a catalog page with some NEAT gadgets that I haven't seen before.
1. Inductors were the arthropods of pre-Cambrian radio, assuming all sorts of truly strange forms with strange names. These balloon circloids appear to be hollow-core toroids. The jewel-box for the kit of three is an especially luxurious touch.
2. The 5-tube kit using the circloids shows how each one mated with a variable condenser; but the interesting part of the kit is the chassis. It's an open frame, with a phenolic section for the tube sockets. Getting very close to later printed circuit boards. (Ebay has one of these for sale. I'm severely tempted, but I'll resist.)
3. Walking detector! Not clear how it worked; appears to have two cams, each moving a separate catwhisker. Presumably the cams were coordinated so the two catwhiskers would 'walk' across the surface of the crystal? How? I need to find more detail, or the patent. (Ebay doesn't have one of these. If it did, I'd buy it immediately.)
From other ads it's clear that Erla was focused on serving experimenters. They made easy-to-use chassis like the above, breadboardable components, and solderless connections. These devices would have made experimenting much easier than metal chassis, but the high plate voltage of most tubes would still be an unnecessary barrier.
Erla went out of the component and kit business soon, but later reorganized as Sentinel, a well-known brand making a variety of radios from battery-powered farm radios to fancy auto-tuned consoles for 30 years. Erla was in downtown Chicago; the Sentinel factory in Evanston still exists and is part of Northwestern Univ.
= = = = =
Here's a lost and later-refound gadget, a linear pot, with an ad that probably wouldn't work today....
Dirty thoughts were simply not at the front of most minds in 1925. Separate mental spaces. Also, suggesting a mass meeting would be STRICTLY VERBOTEN in ads today, unless the ad specified with great precision that the mass meeting was solely for Individuals Of Correct Colour and Correct Gender and Correct Party Label as of the Current Microsecond.
1. Inductors were the arthropods of pre-Cambrian radio, assuming all sorts of truly strange forms with strange names. These balloon circloids appear to be hollow-core toroids. The jewel-box for the kit of three is an especially luxurious touch.
2. The 5-tube kit using the circloids shows how each one mated with a variable condenser; but the interesting part of the kit is the chassis. It's an open frame, with a phenolic section for the tube sockets. Getting very close to later printed circuit boards. (Ebay has one of these for sale. I'm severely tempted, but I'll resist.)
3. Walking detector! Not clear how it worked; appears to have two cams, each moving a separate catwhisker. Presumably the cams were coordinated so the two catwhiskers would 'walk' across the surface of the crystal? How? I need to find more detail, or the patent. (Ebay doesn't have one of these. If it did, I'd buy it immediately.)
From other ads it's clear that Erla was focused on serving experimenters. They made easy-to-use chassis like the above, breadboardable components, and solderless connections. These devices would have made experimenting much easier than metal chassis, but the high plate voltage of most tubes would still be an unnecessary barrier.
Erla went out of the component and kit business soon, but later reorganized as Sentinel, a well-known brand making a variety of radios from battery-powered farm radios to fancy auto-tuned consoles for 30 years. Erla was in downtown Chicago; the Sentinel factory in Evanston still exists and is part of Northwestern Univ.
= = = = =
Here's a lost and later-refound gadget, a linear pot, with an ad that probably wouldn't work today....
Dirty thoughts were simply not at the front of most minds in 1925. Separate mental spaces. Also, suggesting a mass meeting would be STRICTLY VERBOTEN in ads today, unless the ad specified with great precision that the mass meeting was solely for Individuals Of Correct Colour and Correct Gender and Correct Party Label as of the Current Microsecond.Labels: defensible spaces, Entertainment
¶ 9:10 AM
