Issued Patents 1989
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4864224 | Measuring method for determining the difference between an A-C voltage and another voltage, as well as a measuring device for carrying out the same | Guenter Roppelt, Fuerth Schick | 1989-09-05 |
| 4858153 | Method and apparatus for fixing an instantaneous measured value | Carl W. Clever, Gunter Roppelt | 1989-08-15 |