The 1971 West German Porta PUW 2001 (with date only) has the coil on the balance wheel, three fixed magnets with separate electronic components (3 transistors, 3 resistors and 1 capacitor). These rare watches were only produced for a very short time. There is also a PUW 2000 without day or date and PUW 2002 with date and day.

The Porta PUW 2500, 2501 and 2502 movements moved these individual electronic components into a single integrated circuit.

PUW 2001 movement from a Helbros watch:

PUW 2501 movement from a ZentRa watch: