"NIGHTPRO Aurora LED Headlight" Instant on Mod

[Ricky_nz]

I brought 2 of these on special for about nz$75 each a while ago and they are not too bad. I brought the version that takes 3xAA batteries with the intention to run them off the pack power.
Since I have 2 on the handle bars for more visibility ( not a single point source as a higher power unit would be) turning them on is a pain. 3 quick pushes each to get them into full beam.

I want them to come on when the bike is powered up, preferably at full brightness on the main beam, ignoring the small constant / flash group on 5mm leds at the top.
I have for a while now been running an older halogen light during the day since the law in NZ recently made it a requirement for motorbikes and I figured I should do on my ebike due to the minimal impact on main pack energy and the extra visibility is always good.

Preliminary investigation:
http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en010102
The PIC12C508 is a one time programmable microcontroller
The D311 is a single-channel constant current LED driverhttp://www.google.co.nz/url?sa=t&so...sg=AFQjCNFDlD3l55Qp8D1CM2vjnwbQo65rdA&cad=rja
CDT7025 Low voltage detect chip 2.55V http://www.google.co.nz/url?sa=t&so...sg=AFQjCNF6JCS2FS2BVSyWTdKOrvLDEEH-4w&cad=rja

I will have to do some research to see if there is a flash based PIC in the same footprint (Don't want to mess with OTP chips) otherwise I may just bypass the pick and hardwire the constant current generator to the high current level.

since all critical datasheets are available modifing it should be easy and the PCB looks simple.


The running off pack power is easy for my 300W bike as its 24 V and I already run a turnigy BEC to giver 6V for the old halogen
http://www.hobbyking.com/hobbyking/...roduct_Name=Turnigy_5A_(8-40v)_SBEC_for_Lipo_

 

[Ricky_nz]

After looking at the PCB
GP1 of the PIC is connected to enable on the DD311 LED driver.
GP2 of the PIC is connected through a 100R (R4) resistor to the I reference input of the DD311.
In full brightness mode both IO pins are high. I measured about 3V when running of three very flat alkaline batteries..

The PIC power supply pins are connected directly to the battery. This limits the supply range to 2.5 - 5.5V
There seems to be around 3V dropped across the LED

I have applies a simple hack and now it turns on immediately on power connection and the button still works to control the small LEDs on top.
I'm temped to force the small LEDs on also since they are just connected to another IO line.

The mod I performed:
1) remove R4 and reattach rotated to the pad connected to the DD311 IRef input.
cut track between 12C508 pin 6 (GP1) and pin 5 on the DD311 Enable.
solder a piece of 20A fuse wire between the free end of the rotated R4 and the +battery input.
solder another piece of wire between the now isolated pin 5 of the DD311 and +battery (the first wire runs right past).

Edit: If you want the LED's at the top on all the time also Remove R6 from its pads and connect it between the pad closest to the LEDs and +vbatt ( +cap lead on PIC pin 1)

First one modded.


Second one. only w wire links and 2 resistors turned round.
Ok one turned and one replaced. R6 flicked off my tweezers never to be found again (0603 in carpet, think needle in haystack) so I replaced it with an 0805 10K I had handy. R4 is now better attached to the board as its between pin 5 of the DD311 and its origional pad rather than one end in the middle of nowhere as in the origion mod.



With the mod above all LEDs light up immediately on power up. I wonder what constitutes a headlight in NZ law. The law states that a bicycle is allowed upto two headlights and only one is permitted to flash.
My view is one 3W LED + 3 smaller ones in one case constitutes one headlight as it is a single unit.