dalal@topaz.rutgers.edu (Mukesh Dalal) (08/28/87)
I am looking for an electronic circuit diagram for flashing indicators, like those used in automobiles to indicate turns. Any help (pointers, etc.) would be appreciated. Thanx. -- Mukesh Dalal Voice: (201)-878-1763 Dept. of Computer Sc. (Rutgers) Net: dalal@topaz.rutgers.edu
gene@cooper.UUCP (08/31/87)
in article <14297@topaz.rutgers.edu>, dalal@topaz.rutgers.edu (Mukesh Dalal) says: > I am looking for an electronic circuit diagram for flashing > indicators, like those used in automobiles to indicate turns. How about just taking a 555 in conjunction with a power relay? 555s are pretty insensitive to power supply fluctuations, VERY stable, and can sink/source up to 100 (200?) mA. The relay could be used as a switch for the indicator lights. Points to remember: * if the 555 output can't sink/source enough current, a power transistor with appropriate ratings can be used as a buffer. ALWAYS heatsink the thing, even if it just gets warm on your workbench; in a confined space, such as in a car nook or cranny, heat could build up to a dangerous (for the xstr) level. * remember to install a freewheeling diode across the relay coil to kill off inductive spikes. * use the formulae D = ( Ra + Rb ) / ( Ra + 2 Rb ) /* duty cycle */ f ~= 1.4 / ( Ra + 2 Rb ) C /* frequency */ from the "schematic" +V O pins |----- (8) Ra Z |----- (7) Rb Z <555 connections> |----- (2,6) C === |----- (1) --- /// > Any help (pointers, etc.) would be appreciated. char *s; struct foo *fooptr; float *f; (I couldn't resist! ;^) ) Gene ...!ihnp4!philabs!phri!cooper!gene "If you think I'll sit around as the world goes by, You're thinkin' like a fool 'cause it's case of do or die. Out there is a fortune waitin' to be had. You think I'll let it go? You're mad! You got another thing comin'!" - Robert John Aurthur Halford