| T O P I C R E V I E W |
| petedao |
Posted - 25/04/2008 : 07:15:30
Hi,
I have followed the instruction on http://www.gadgetvenue.com/how-to-build-your-own-led-light-bulb-07305105/ to build my own LED light bulb.
Now, I want to incorporate this with some sort of power management IC. The questions I have are:
1. Where can I buy those power management IC for the light bulb? Is it part of the LED driver? If so, where can I purchase one?
2. How do I connect the IC with the light blub?
Any input will be greatly appreciated.
Thanks,
Pete |
| 2 L A T E S T R E P L I E S (Newest First) |
| ghurd |
Posted - 25/04/2008 : 22:09:23
I hope you read the replies to that post, about a 12V LED bulb having 3 LEDs per string instead of 4.
I frown upon overly complex stuff. I like plain and simple resistors.
Capt's voltage regulator is the next best thing, and I agree with him.
I don't think a circuit is any good unless it can be used.
If there are 4 white LEDs of reasonable quality, it would be possible to use a 7812 voltage regulator, and add a 240 ohm resistor between its ground pin and true ground. That would bring it up to about 12.6V output, about 3.15V per LED, which is close to 17.5ma per LED.
Every LED is different. The ma need to be measured.
If the current is too much, reduce the resistance. If the current is below 15ma, increase the resistance slightly.
It would work best with a low drop-out 7812. And the battery voltage will need to be about 13.5V to work properly.
If it has 3 LEDs, and you insist on using a regulator, then a 7809 and a 180 ohm resistor. Everything else as above.
The regulators should be 1A and TO-220 size, minimum.
78xx ICs are available about everywhere in the world. Shouldn't cost more than $3.
G-
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| Capt Slog |
Posted - 25/04/2008 : 08:50:31
I think it's frowned upon in electronics circles, but I use these...
http://www.reuk.co.uk/buy-LM2940.htm
Those in the know seem to make current regulators, whereas these regulate the voltage and by that the current stays constant if nothing else changes in the bulb.
I'm using one of these for each lighting circuit.
How much did it cost to build your bulb by the way? I've managed to pick these up for £3.69 each, and they have a rectifier built in which allows them to be plugged in either way around.
(editted to include photo, now a memeber of Photobucket ) |
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