A
andy
- Jan 1, 1970
- 0
I've built the following circuit on breadboard as a dimmer circuit for 3
luxeon III Star ultrabright LEDs:
http://www.niftybits.ukfsn.org/electronics/luxeon-dimmer.png
any comments welcome. It does work at the moment, but when the battery is
low, the maximum current drops from 0.9 A to 0.7 A, and the op-amp swings
near to the top rail. The one thing I'm thinking of changing before I
solder it up is to change the 1 ohm sense resistor for a lower value
(maybe 0.5 ohm) so that the transistor has a bit more headroom to work
with, which should cure this I think.
The LEDs are /very/ bright by the way - 3 of them are enough to light a
small room well enough to read by. The light is a bit unkind on the eyes,
but not too bad. 3 at full current are about equivalent to an 11 Watt
energy saving fluorescent light bulb, which puts them in roughly the same
bracket as far as efficiency goes.
luxeon III Star ultrabright LEDs:
http://www.niftybits.ukfsn.org/electronics/luxeon-dimmer.png
any comments welcome. It does work at the moment, but when the battery is
low, the maximum current drops from 0.9 A to 0.7 A, and the op-amp swings
near to the top rail. The one thing I'm thinking of changing before I
solder it up is to change the 1 ohm sense resistor for a lower value
(maybe 0.5 ohm) so that the transistor has a bit more headroom to work
with, which should cure this I think.
The LEDs are /very/ bright by the way - 3 of them are enough to light a
small room well enough to read by. The light is a bit unkind on the eyes,
but not too bad. 3 at full current are about equivalent to an 11 Watt
energy saving fluorescent light bulb, which puts them in roughly the same
bracket as far as efficiency goes.