1. Tube tetrode with directly or indirectly heated cathode.
2. Reverse blocking tetrode thyristor; semiconductor controlled switch.
3. Reverse conducting tetrode thyristor; semiconductor controlled rectifier.
4. A tetrode with grid and plate potentials so arranged that plate current decreases when plate potential increases.
5. Drag onto the page to add a tube tetrode with directly or indirectly heated cathode.
6. Thyristor , reverse - blocking tetrode - type ; semiconductor controlled switch. Envelope can be shown or hidden.