Electronic circuit for optical or capacitive sensors of control keys

摘要

It is an electronic circuit 1 for optical or capacitive sensors of control keys, which comprises a narrow band amplifier 2 which receives the pulse trains arriving at the receiver 9 of the sensor 7 when a key pulse is produced, and an envelope detector 3 by means of which the envelope of the output signal of the amplifier 2 is obtained. The amplifier 2 has a transistor T1 polarised at a point near the cut-off condition, and the detector 3 in a first embodiment is comprised of a transistor T2, a capacitor C4 and a resistor R10. <IMAGE>