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DX P7 Bike light MEGA MODE

19K views 26 replies 17 participants last post by  jetigm 
#1 · (Edited)
Hi all :) First of all sorry for my English, hope it good enough to understand what I done :)
Her is my HA-III SSC P7-C (SXO) 3-Mode 900-Lumen LED Bike Light Set mod. The project is free, so any who have proper skills can do this improvement.
After several times of using this pretty cheap bike light, I find bad usability of this product. The flashing mode is useless, we have no "low" mode and the cycling mode selection with turning off as for me is not very comfortably. So I decide to build my own "computer" which realize each of my desired mode :)

Ho to use:
Fast click to turn on the first mode.
3 mode's are available:
1. "low"
2. "mid"
3. "high"
Mode's selection is cycling by fast click (< 0.5 second):
-> low -> mid -> high ->
|__________________|
Holding switch more than 0.5 seconds in any mode turns off the P7.
When the batt go to discharge level, the red led is on and mode go to previous if it was "mid" or "high".

Also I rise a current up to 2.5A at P7 by means of current-limiting resistors on driver circuit. At my point those two resistors are not very powerful to work proper at such high current that we have and they are burned out just in time of testing when I switch on and off the P7. So those many 1Ohm resistors which you see on photo is not just to rise the current but also to provide a reliability.

Some photo:
 

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#6 ·
Great stuff but far too much like rocket science for me.

One thing though.. you mention that you didn't like having to cycle through the modes to turn off.

You can hold the button in for around 2 seconds to turn off and the light will come back on in the same mode next time you switch on.
 
#7 ·
yetibetty said:
You can hold the button in for around 2 seconds to turn off and the light will come back on in the same mode next time you switch on.
This doesn't seem to work on mine. The light switches off after the 2 seconds but when I switch on again it's in high mode. Not that that's a huge issue as I generally only use it in high mode anyway. The thing that does annoy me is that when you plug the light in it switches on. Only workaround I've found is to touch the contacts briefly (light switches on for a sec) before plugging in fully.

Mick
 
#9 ·
El34 said:
Cool stuff.

I don't recognize any of those file formats in the zip folders?
Well, schematic and PCB you can see in .jpeg, the PCB is simple so you can draw it in you favorite format, and here is just .hex files of firmware and some explanation how it works, that if you don't have CVAVR. Actually I don't know, maybe ATMEL for you is an exotic :). Flashing ATTINY13 is no problem i think - I use simplest AVR ISP programmer (5 wires from LPT port).
 

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#10 ·
Der Umbau gefällt mir.
Aber wieso verwendest du 0,079Ohm für den Strombegrenzugswiderstand und nicht etwas weniger, damit du auf 2,8 A kommst (0,0714 Ohm)?

Why did you use 0.079 Ohm resitor for current limiting?
I thing it is better to use a liitle bit smaller resistor like 14 times 1 Ohm.
(0.07 Ohm + wireresistor and transferresistors)
Then it is possible to have a forward current of 2.8 Ampere.
 
#12 ·
Want to make a few for some others?

PIC programming and soldering etc are all within my skill set, but PCB building and sourcing various individual parts can be a pain/costly.

Seeing as you have mode memory, I don't see why you couldn't keep the strobe (or change it to flash), since that would be nice for day time cycling (for roadies).
 
#14 ·
Hi cool mod!

So if I understand this right, you removed some parts on the original controller, built a daughter board with the tiny13 and vcc supply on it on it and then control the driver via PWM from this?

Rather than using a lot of 1E resistors you can achieve the same with a single smt (maybe 2512?) resistor, they are available in a bunch of low ohmic values.
 
#18 ·
If I good understand, if I only change resistors (will make less Ohm) I will have more mA on output? After upgrade (2.4A -> 2.5A) I will have +~30lm? It feel in real life? How about battery life? Light will burn less time after upgrade, interesting how much less, maybe anybody tested it?
 
#19 ·
Yes, it will increase the current.
After upgrade (2.4A -> 2.5A) I will have +~30lm? It feel in real life?
Not much.
How about battery life?
Approx the same time, maybe just a little less, but not much.

You should upgrade the resistors primary to get reliable work, increasing current is a game that give you almost nothing.
 
#22 ·
I replace resistors, to 13 resistors 1Ohm, before I have 2.4A output and now 2.7A. I don't want increase so much, but I will test it... I'm thinking about to hight temperature protection, maby someone know simple way, how to make it? If temperature to hight, I think light must go to mid mode.
 
#26 ·
This is great. OP, commendable effort for a DIY and huge thanks for sharing.
Question, why did you opt to go with a LM317? That's a very inefficient way of regulating the voltage; why not a switching regulator?

_MK
 
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