These were not the first movements with a transistor; the Bulova Accutron can claim that but the ESA 9150 Dynotron, launched in 1967, was the first movement with a balance and a transistor.

Judging by the number of watches that are still around today, running quite happy with these movements, the Dynotrons must have been a very successful movement for ESA. In addition, many watch companies employed Dynotron movements in their watches. There were four main calibres:

• ESA 9150: 1967, the first electronically controlled balance wheel movement, date, running at 21,600 BPH.
• ESA 9154: 1970, date, increased to 28,800 BPH; 9150 and 9154 look very similar.
• ESA 9157: 1975, date, 28,800 BPH.
• ESA 9158: 1975, day and date, 28,800 BPH; 9157 and 9158 look very similar and do not have the quality of the earlier 9150 and 9154.

In addition to the four main calibres above, there was also:

• ESA 9159: from the balance side, identical to the 9157/8 calibres but lacked hands. It was only ever used in the very rare Gruen Electronic Jump Hour watch.
• ESA 9176: a very strange movement that was used in the Jaz-Derby Swissonic
• ESA 9200: a small calibre that was often used in ladies watches (see Lukcom).

ESA 9150

ESA 9154

ESA 9157

ESA 9158

ESA 9176

ESA 9200