Example LED Driver Circuit
Running an LED with pulses to get maximum
brightness
To give maximum brightness an LED needs to be driven by a
pulse circuit. In this way, it is possible to put 0.5 Amp
current pulses through an LED at a frequency of around
100Hz which fools the eye into thinking that it sees a
continuous light.
If the LED is run at 0.5 Amps for very long, it will
burn out (usually within a fraction of a second). By
keeping the pulse duration relatively short, we can avoid
overheating the LED.
This circuit allows adjust ment of the pulse width so
that the maximum average current is no more than
50mA.
To ensure long LED life, it should be adjusted for
maximum brightness then reduced slightly to an average
current of around 40mA. One or two LEDs can be driven
simultaneously. C1 can be around 1000uF and acts as a
reservoir because the average battery is unable to supply
half Amp pulses of current. The circuit can be run from a
battery or dc supply of 9 to 12 volts.
We had intended to supply all the parts as a
kit but we've had only 2 enquiries in two years.
However, you should be able to order all the
components from Maplin Electronics in the UK.
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