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.