movement detector

3-30 — elektor march 1981 movement detector I nspite of the fact that an electronic movement detector is used in many department stores and office blocks nowadays, a great number of people still think it something of a mystery when the doors slide open automatically as they approach the exit with a loaded trolley. In vain they look for the "thing" that noticed their presence. In some cases it is a shaft of light catching passing legs, but usually the method of detection will be invisible and therefore all the more mysterious. The system described here not only opens doors but also switches lights on and off and can in fact even be used for a game, the purpose of which is to sneak out an object from a guarded room (good practice for burglars!) Parts List. Resistors: R1 = 12 M R2 = 1 M R3,R15 = 10 k R4 = 15 k R5,R6 = 47 k R7,R21 = 470 R8 = 33 k R9,R10 = 4k7 R11,R16 = 470 k R12,R13,R14.= 100 k R17,R18 = 22 k R19 = 2k7 R20= 1k2 R22 = 1 k P1 = 220 k preset P2 = 100 S2 /1 W, linear Wh...