timer scheme:
This arrangement is of course nothing but a shot but is particularly well suited to
environment "aggressive" of an automobile. As shown in Figure! We use a CMOS door
Schmitt trigger. Pressing the push load instantly Pi Ci condensates which can no longer unload then slowly than in Ffe.Meanwhile the output of the gate Id is at logic low level which saturates Ti and T2 thus feeding the bulbs pilot lights of the vehicle. You will notice indeed that T2 is in fact connected in parallel with the normal ignition from these demieres. The power supply circuit of a car being the seat of violent CAUSED surges, both by the ignition circuit by motors and electromagnets contained in various accessories, zener diodes are DZ2 DZi and to protect the IC from any destruction. The particular position DZ2 is surprising. In fact, it allows to avoid that presented surges on the supply line can reach the exit of IC1 via R5 and the base junction of T1 -emetteur
Electronic composabtes: IC: 4093 CMOS Ti: A 2N2905 or 2N2907 A T2: 2N3055 DZi, DZ2: zener 15V / 0.4W Ri: 1 Y £ l 1/4 W 5% Cmarron, black, red] RZ 470 kQ 1/4 W 5% [yellow, purple, yellow) R3, R4: 100m / 4W5% Cmarron, black, brown] Rs 6.8 kQ 1/4 W 5% [blue, gray, red] Rg: 4 k l £ 7 1/4 W 5% (yellow, purple, red] The 100 uF / 25V Neck radial chemical information, see text] Cz 100 uF / 25V radial chemicalPi push has work contacts [contact by pressing ] 1 IC 14 has support legs contacts tulips
