Abstract: An impact printer has a flux regulator for each of the coils in its printhead. Each regulator provides a reference voltage indicative of the desired flux in the associated coil. A circuit is provided for measuring the flux in the coil and for providing a voltage representative thereof. The measured flux representation is compared with the reference flux representation and any difference is applied to a power circuit which then provides more or less power to the associated coil.

Abstract: A system is disclosed for marketing merchandise or services by telephone using brief prerecorded audio demonstrations stored in an audio program repeater and connected to a customer's telephone line by a switching system under control of a data processor in response to a code entered by a customer service operator via the switching system or a code entered directly by the customer through his push-button telephone. In the latter case the data processor is in direct communication with the customer who uses the telephone push buttons to respond to prerecorded messages transmitted from the audio program repeater under control of the data processor. Otherwise the customer communicates with a customer service operator through the switching system and the customer service operator in turn selects the demonstration through the data processor.