When I started flying it was this sort of ADF along with a ribbon DI
http://thumbs.ebaystatic.com/images/...roP/s-l225.jpg
Nowadays you can visualise where the needle should be on the DI, with the ribbon DI you really had to work it out in your head.
Even worse was doing the RN Observers course in the Sea Prince, in that you were often working off marine beacons - these only transmitted for a set period, IIRC something like 2 minutes every 10 minutes, it was a "coffee grinder" ADF setup operated by the pilot where you set the frequency, idented the beacon then actually rotated the aerial to get the bearing! This was then called down to the nav students in the back of the aircraft!