I've come across a VGA to PAL composite converter that calls for a video
'delay line' of 400ns.

I looked through my junk and discovered two such modules. They are branded
with the Matsushita triangle, and have such cryptic part numbers as VLD0014
and EFD-EN645, respectively.

I know what digital delay lines are (and how they can be built cheaply from
slow logic gates), but I am not familiar with analogue delay lines. What's
inside these black boxes (literally, they are black and square) I know that
RC/RL circuits introduce phase shifts, is this how they work. I've noticed
that one such device is represented on the schematic with a tapped inductor
symbol. It's hard to imagine why they are so hard to get hold of.

The ones I have have four legs, but the circuit specifies one with three
connections - Does anybody know anything about these specific devices I
mentioned, and whether they are suitable substitiution for a 3 legged
device?

Thanks

Peter L.

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