Hello everyone, I've been doing a ton of research for retrofitting LEDs into my scooters turn signals, I'm currently working on a prototype version of it.
So far I bought 12 Amber Lumileds Superflux Model: HPWT-ML00-0000, I've decided to do a 4x3 array, consisting of 4 strings with 3 LEDs per string.
From what I understand in the datasheet the LEDs should be runned at 50mA-70mA with a forward voltage between 2.19v-3.15v (2.6v nominal) @70mA.
From some the service manual of the bike, max voltage is 18v, with 14v charging, and about 12.9v with a fully charged battery. The turn signal only has two wires, +12v power and ground.
I've seen many different ways to power the LEDs, I'm wondering what everyone thinks is the best way to go. So far I've seen:
1) The simple current limiting resistor in each string.
2) The LM317 regulator with a resistor between the adj and out to make it a constant current.
3) The circuit that uses an NPN transistor, a N-channel FET, and 2 resistors.
4) The sense pass current regulator.
5) The switching current regulator.
I also want to ask about incorporating something called EMC transient protection which looks like a silicon diode in series with the LEDs, and a zener diode wired in parallel, is this a good thing to have or is it unnessesary?
Here's some circuit diagrams of each, the LED array I'd like to use is 4 parallel connected strings with 3 leds per string.
1) simple resistor method with that EMC protection
2) LM317 method
3) NPN transistor method
4) and 5) Sense pass and switching method
So far I bought 12 Amber Lumileds Superflux Model: HPWT-ML00-0000, I've decided to do a 4x3 array, consisting of 4 strings with 3 LEDs per string.
From what I understand in the datasheet the LEDs should be runned at 50mA-70mA with a forward voltage between 2.19v-3.15v (2.6v nominal) @70mA.
From some the service manual of the bike, max voltage is 18v, with 14v charging, and about 12.9v with a fully charged battery. The turn signal only has two wires, +12v power and ground.
I've seen many different ways to power the LEDs, I'm wondering what everyone thinks is the best way to go. So far I've seen:
1) The simple current limiting resistor in each string.
2) The LM317 regulator with a resistor between the adj and out to make it a constant current.
3) The circuit that uses an NPN transistor, a N-channel FET, and 2 resistors.
4) The sense pass current regulator.
5) The switching current regulator.
I also want to ask about incorporating something called EMC transient protection which looks like a silicon diode in series with the LEDs, and a zener diode wired in parallel, is this a good thing to have or is it unnessesary?
Here's some circuit diagrams of each, the LED array I'd like to use is 4 parallel connected strings with 3 leds per string.
1) simple resistor method with that EMC protection
2) LM317 method
3) NPN transistor method
4) and 5) Sense pass and switching method