Issued Patents All Time
Showing 1–3 of 3 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4684927 | Annunciator circuit for elevator systems | Marlin O. Thurston | 1987-08-04 |
| 4664764 | Cathodic protection of structures | — | 1987-05-12 |
| 4653093 | Frequency selective ringer circuit | — | 1987-03-24 |