flash a led from a single cell
1.5 Volt LED flasher
flash a led from a single cell
Introduction
With this circuit it is possible to operate a LED from a single
1.5 Volt cell. The LED will flash
about every second.
Circuit description
R1, C1 and IC1B build a slow oscillator (about 1 Hz).
When the output of IC1B is low, the outputs of IC1A/D will become
high and the outputs of IC1C/E will become low:
C2 is now charged to 1.5 Volt
When the output of IC1A becomes high, the outputs of IC1A/D will
become low and IC1C/E will become high:
Charged capacitor C2 is now switched "in series with"
the battery voltage: C2 is discharged through the LED until the
voltage
of the battery and C2 together is lower than the LED forward
voltage.
IC1A/D and IC1C/E are put in parallel to increase the peak
current trough the LED.
Note: red LEDs have lower forward voltage and will therefore work
best with this circuit; the best choice will be a high
efficiency red LED.
Led flasher schematic:
Picture of the assembled circuit:
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components at the
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