12-11-2024, 08:05 PM
(This post was last modified: 12-11-2024, 08:07 PM by Mike Watterson.)
I think they are staggeringly fine wire and high impedance. Maybe more than 45K. My 1935 pickup https://www.radiomuseum.org/r/hismasters_370.html was O/C but corroded just at end of coil, so repairable.
It gives quite high output even with a bamboo cocktail stick. The steel needles are "single play", which is why 1930s USA autochangers used sapphire. Some of those played both sides. An Album might have been 5 off 12" 78s, pressed in order to allow flipping the stack, as they came in a photo or scrap-book style "album" book.
I'd expect O/C to be many megaohms. Feed direct to a working amp to text, or scope.
After 1928, Columbia, HMV and Marconiphone (consumer) were just EMI brands, but EMI even in 1950s mostly only used the EMI brand for broadcast and studio gear.
Quote:The moving iron Pickup coil uses unbelievably fine wire, with about 42500 Ohms (42K5!) on about a 15mm bobbin about 5mm tall winding.
It gives quite high output even with a bamboo cocktail stick. The steel needles are "single play", which is why 1930s USA autochangers used sapphire. Some of those played both sides. An Album might have been 5 off 12" 78s, pressed in order to allow flipping the stack, as they came in a photo or scrap-book style "album" book.
I'd expect O/C to be many megaohms. Feed direct to a working amp to text, or scope.
After 1928, Columbia, HMV and Marconiphone (consumer) were just EMI brands, but EMI even in 1950s mostly only used the EMI brand for broadcast and studio gear.
