we pronounce it as 'ed-id' when the base verb end in one of these sounds
t/ want-edd/ end-ed

we pronounce it as 't' when the base verb end in one of these sounds
p/ hope-d
f/ laugh-ed
s/ fax-ed
S/ wash-ed
tS/ watch-ed
k/ like-d

we pronounce it as 'd' when the base verb end in one of these sounds
all the other soundsexamples: play-ed, allow-ed, beg-ged..etc