1. CIRCUIT IDEAS
FLASHING BEACON S.C.
DWI
VED
I
ASHOK K. DOCTOR the figure. The IC is pro-
vided with an aluminium
A
flashing beacon has many uses. It heat-sink to dissipate the
can be employed as a distress sig- heat generated while deliv-
nal on highways or as a direction ering full current. Since the
pointer for parking lots, hospitals, hotels, IC has an inbuilt switch-on
etc. Here we present a flashing beacon current limiter, it extends
that uses well-known regulator IC LM317T. the bulb life.
As LM317T regulator can deliver more than For the shown values
1 amp. A small 12V, 10W bulb with a of resistors and capacitors,
high-quality reflector can serve as a good the bulb flashes at approxi-
visible blinker. mately 4 cycles per second.
A 12-15V, 1A DC supply is connected The number of flashes de-
to the input pin of the IC. A 12V, 10W pends on the charge-dis-
bulb and a combination of resistors and charge time of the capaci-
capacitors are connected between the out- tors. Different values of resistors and ca- crease the number of flashes.
put pin and ADJ pin of the IC as shown in pacitors can be used to increase or de- This circuit costs around Rs 50.
NOVEMBER 2002 ELECTRONICS FOR YOU