Abstract: A completely automatic suppression of an echo in a video signal is accomplished by using a multiplying circuit in the amplitude and polarity control of a correction signal which must compensate for the echo and an automatic control of the time delay of the correction signal by means of an echo polarity correction switch with which the polarity of the setting of the delay control characteristic is matched to the polarity of the echo to be suppressed.

Abstract: Apparatus is disclosed which functions to adjust the moisture content of casting sand as it is being recovered, so that the sand may be re-used without significant or further adjustment of its water content. The apparatus includes a cooler-drier which receives hot castings and sand and discharges the sand and castings separately. A water spray impinges upon the sand and castings as they are moved through the cooler-drier and a temperature sensor which senses the temperature of the sand/castings mixture at the inlet controls the water spray so that the discharged sand possesses a uniform and selected moisture content.