All components required to activate a continuously adjustable valve (not just for amplifiers) are housed on a card (normally with a European format) (Figure V 19). This includes not only control amplifiers, but also adjustment elements for desired and actual values, adjustment for the underlying regulators or the prescribed transfer element and the adjustment. In exceptional cases, the electric power supply may be housed in the card, e.g. if a central electric power supply is not justified due to the use of not only one amplifier card.
Figure V 19: Amplifier card