[GreenKeys] wire spring relays

[Charles Ring W3NU]

This is not directly related to TTY but I know there are a number of 
Bell Telephone veterans here, so...

I recenty bought on ebay 60 pounds of W.E. wire spring relays, which I 
have used for years for broadcast audio switching. The best relays in 
the world. This lot consists mainly of 4 rack panels, each with 8 dual 
relays, each side of each relay having five form C contacts (ideal for 
my purposes). My first surprise was that each side of each relay has a 
soldered-in 1200 ohm 1 watt resistor in series with its coil, and the 
coil resistance is only 90 ohms, using magnet wire heavier than usual. 
It takes about 90 mA to pull in the armature, and the biggest surprise 
was that upon removing the current the relay stays pulled in, 
indefinitely. It takes a current pulse of opposite polarity, less than 
it takes to pull it in, to release the relay. I've seen delayed-release 
relays before but not this. I see nothing physically obvious to make 
them behave this way. Each side of each relay has a number from 0 to 15 
stamped on it, so I guess what I have is four hexadecimal magnetic 
memory units.There are no SD or BSP numbers on any of this.

1. Is my guess right that these are memory relays and I could reliably 
use them as such? Do they stay pulled in long-term?

2. Is there any way to change them to normal relay operation?

3. How are they made to behave this way? Some magnetic material that 
stays magnetized long-term? I don't have a normal dual relay to compare 
them to on hand.

4. Is there another list or forum where this subject would be more on topic?

Thanks and 73 de W3NU