DUAL
MODE LED FLASHER
This LED flasher is built around
timer 555. The circuit is very simple
and self depictive. It is a free running
oscillator, oscillating at 1 Hz rate approximately. Transistor Q7 is used to control LED
mode. When high logic is given to the
base of Q7, pin 2 of IC1 is pulled down below 2/3rd of VCC resulting
in high output at pin 3 and LED D3 glows constantly. The low logic at base of Q7 keeps LED
flashing. It can be connected to many
circuits. For example Automatic Battery
Charger showing two states of charger
i.e. battery charging and battery charged.
It can be connected to 12 V battery charger as it is. However, for 24 V charger any of combination
shown in fig 2 or 3 may be added. Since IC 555 works fine if connected to +5 to
+15 volts (Min-Max).
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