Relay computers

From: Gordon JC Pearce <>
Date: Sat Sep 25 06:09:29 2004

Tony Duell wrote:

> There were/are also relays with 2 coils. The idea is that either coil
> alone will activate the contacts, but if you energise them both together
> (in opposite directions), the magnetic fields cancel out, and the
> contacts don't operate.
> And of course there are magnetically-latched relays (effectively SR
> flip-flops).
> -tony

And slugged relays, with a big metal ring in the coil. These either
delay opening or closing, but I can't remember which way round it works.
  I've got a few from old telephone exchanges - when I was about 12 or
13 I convinced my Dad to take a pickup truck full of BT phone exchange
"modules" from the local scrapyard.

Received on Sat Sep 25 2004 - 06:09:29 BST

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