On_off_touch_switch

Published:2009/7/21 23:44:00 Author:Jessie | From:SeekIC

This circuit uses a CA3240E to sense small currents flowing between contact points on a touch plate, which consists of a PC board metalization grid. When the On plate is touched, current flows between the two halves of the grid, and causes a positive shift in the output voltage (pin 7) of the CA3240E. These positive transitions are fed into the CA3079, which is used as a latching circuit and zero-crossing triac driver. When pin7 of the CA3240 is positive, the triac and lamp are on. The opposite occurs when the Off plate is touched, and pin 1 of the CA3240 is positive.



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