Casing: ABS plastic, “Teko” company (Italy).
The device is built on two LSI’s made by “Intel”. One LSI was responsible for action, the other — for expert evaluation.
Indication: LEDs displayed energy level, action mode, and expert evaluation. Two action modes — continuous and intermittent.
Power supply: replaceable galvanic cells or accumulators, size AA.
This is a modification of the 611, but now it is built with one LSI (again “Intel”) of larger capacity. This provided the device with its famous “indestructibility” and robustness.
The socket for connection of remote electrodes which was implemented in this device became a standard for all other manufacturers.
This is neither modification of the 611 or the 612, though casing is the same.
Two output stages with automatic switch-over.
Two-line character LCD-display showed all operating modes and expert evaluation. This is the first device where expert evaluation was displayed on LCD indicator.
Power supply: built-in rechargeable accumulator (recharged automatically from the replaceable accumulators and mostly served as backup battery, i. e. the device would work even if the replaceable accumulators were down or taken out). Basic accumulators were replaceable — two galvanic cells or rechargeable batteries, size AA.
The first casing from OKW company, ABS plastic.
This is the smallest device ever produced before. No one had ever made a device smaller than this. It is a smaller copy of the 612. The same LSI but in a smaller size casing.
Power supply was special: galvanic cells of size N.