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Yet, by using some
super bright green surface mounted LEDs from King Bright, the effect is quite impressive
even if each LED is driven with only 2ma of current.
The circuit
completes a cycle of the 10 LEDs once each second. A LMC7215 low power voltage
comparator is configured as a 10Hz 20ms pulse generator. This 10Hz clock is fed to a
74HC4017 decade counter. The 4017 is unique in that it has 10 outputs which turn on
sequentially with each leading edge of the clock input. The LEDs are all ganged
together and connected to a constant 2ma sinking current circuit. As the battery
voltage drops, the circuit will maintain a constant 2ma of current.
The 10 LEDs can be
configured into a loop or a line. A loop display might be handy for dog collars.
A line mode can convey a right or left pointing direction. |
