Flashing LED unit
The circuit given here is designed as an LED flasher which produces a rotating effect when the LEDs are arranged properly. The circuit has very low current consumption and can be operated from even 3V button cells.
The IC 1 (CMOS NE555) is wired as an astable multivibrator wired at a duty cycle of 50% and 4Hz frequency and drives LEDs D1 to D6.The second IC, IC2 (CMOS NE555) is working as a trigger pulse inverter and drives LEDs D7 to D12.The circuit is arranged such that the ICs sink the current consumed by the LEDs. At low operating voltages like 3V, the CMOS NE 555 performs better when arranged in sinking mode rather than in sourcing mode. The LED D13 remains permanently ON.
Circuit diagram with Parts list.
- Arrange the circuit on a good quality PCB.
- The circuit can be powered from a 3V battery.
- The ICs must be fixed on holders.
- The switch S1 can be a slider switch.
- To get a rotating effect arrange the LEDs on a plastic sheet as shown as in the figure.