garage stop light

1110011111041111 A novel use of solar cells makes pos- itioning your car in the garage rather easier than old tyres, a mirror, or a chalk mark. The six solar cells in figure 1 serve as power supply and as proximity sensor. They are commercially available at relative low cost. The voltage developed across potentiometer P, is mainly dependent on the intensity of the light falling onto the cells. The cir- cuit is only actuated when the main beam of one of the car"s headlights shines direct onto the cells from a distance of about 200 mm (8 inches). The distance can be varied somewhat with 1 2 garage stop light Under those conditions, the voltage developed across C1is about 3 V, which is sufficient to trigger relaxation oscillator N1. The BC547B is then switched on via buffer N2so that D3 begins to flash. Diodes D1and D2 provide an additional increase in the threshold of the circuit. The total voltage drop of 1.2 V across them ensures that the potential at pin 1 of 8-01 3 the 4093 is...