Ian repairs, services, & restores amps and associated equipment. He is based in the Basingstoke/Reading/Newbury area, and can be contacted on 07771-504806 or at firstname.lastname@example.org .
The Elpico AC 55 was offered with an "add-on" tremolo circuit as an optional extra. This was a simple unit whose control switch provided a slow or fast effect, together with an off position. The add-on unit can be seen mounted behind the left side of the rear cabinet panel in the above photo.
CIRCUIT DIAGRAM OF THE TREMOLO UNIT: