Help needed with a driver Updated - Question answered - Thanks

I am playing with a light that I got from Tractor Supply. It has an outer ring of green leds and a center white led. The outer ones look like 5mm leds and the center one looks like one of those 1 watt or 3 watt leds on a 20mm star.

EDIT: This is a 3AA in series light. The modes only change the led circuits from green, to both and then to white only.

I want to put a Nichia in the center. That's not a problem, but I want to use the same driver and possible up the amperage to the circuit for the center LED. Here's a photo of the driver.


The circuit outlined in RED, is the one for the green leds. The circuit outlined in BLUE must be for the center led, but is all of it the same circuit or is it something else? I wonder if I could remove resistors to get to where the led got direct current, but still controlled by the program. The light turns on for green, both and white. I don't want to scrap the driver. I want to keep the sequence, but just give the nichia more amperage. I thought I could remove certain resistors and bridge the connections where they were, so I could get direct current.

No? Any ideas? I really do not want to go buy resistors. I would rather just remove certain ones and bridge them, if that would work. What I know about this stuff is to ask someone else before I ruin it, LOL.


Here are two links to FULL SIZE CROPS. I think it will show the traces much better. They are big, so I did not want to put them in here. You have to click on the zoom icon, to see the full size photo. Let me know if this does not work.

Hi OL. I'd love to be able to help you but you know what I'm like with electronics. The only suggestion I have is that the red and blue circles on the driver must mean something. Good luck and cheers.

+1, have a bump though.

I’am no expert but I would guess it’s the resistor marked 471. 470 ohms current limiting resistor. I could be wrong but that’s my guess according to where it is connected on the 2TY. The other circuit appears to be the resistor marked 470 (47ohms).
Probably need a expert here to confirm.

at the entrance to the transistor there are two legs, one is
probably the collector or emitter and the other one is the base, altering the value of the resistors before those legs will alter the flow through the transistor, (for better or worse)
but it will not change the length of the on time.
those resistors may also protect the transistor
and so, lowering their value may burn the transistor.
So what moderator007 suggested seem to be correct
at least to me.

Certainly not an expert here.... but this looks right to me as well. (Gulp) (Shake) (Tremble)

Good Luck... LET US KNOW!!! ...Waiting!!! Dan.

will increase certainty, reduce anxiety, help you lose weight, etc., etc., :smiley:
but reverse engineering this may still be difficult.
It is a rational first step, though. . .

The chip internal circuitry or block diagram with pinout is very important and taking a photo of both sides of the board will allow you to put one photo on top of the other and so be able to tell what components are fastened where when looking at the foil side. It helps to have or make a light table to see through both photos.

Can you make out the full part number on the CX80?? chip?

I see two via holes going straight to both transistors (to LED+), and ground ring to LED-.

Can you confirm if the holes are connected to the +ve battery terminal, and same for -?

If so, I think it may already direct-driven.

What kind and how many batteries does the host take?
Does the driver have modes, and if so, do you still want them?
Can you post a shot of the battery contact side, with the same edge at the top?

The 3 pin SOT-23 marked “2TY” is a PNP Transistor. Looks like its Emitter is hooked directly to Bat. The two “103” resistors are 10K pull-ups on the base and the 470/471 are the base current-limit resistors. The Collector is hooked to the LED

I don’t know what kind of cells this light uses (since you didn’t say), but I’ll do the math for a LiIon and you can adjust as necessary.
Math corrected for three fully charged alkalines (1.3V Each under load)

The “2TY” is actually a S8550 PNP Transistor with an hFE of minimum 50.

The 471 is a 470 Ohm resistor, and at 3.9V would allow
(3.9 - 0.6) / 470 = 7.0mA (the 0.6 figure comes from the turn-on voltage of the Transistor)

(7.0mA * 50) - 7.0 = 344mA minimum.

That transistor is rated for max 0.5A (500mA), so you’re not far from that.

Change that 470 resistor as necessary to make the math work out as you desire.


The light is a 3AA light, using alkalines. The "Modes" are to change from green leds, to all leds, to just the white led. It just changes which leds are on, it does not dim anything.

I edited the OP with links to larger photos, including one that has been bacl lit, to help see the traces.

Photo of the back side is in the OP now. Updated the OP.

Having just been looking at my DST with it’s positive hole for going direct, I also wonder if you can move a wire to go direct and or add your own resistor inline with the new connection.

I seem to remember that CX-804 chip is a RGB LED controller chip. That driver probably started out life as a RGB driver (note the holes for “R” and “G” wires). I can’t find any data on the chip, though. I seem to remember that another company also made it with a prefix that started with “B?” (? is another letter).

This is the first driver I’ve seen that uses biased transistors for current limiting. They probably will get nice and toasty if the current is pushed, especially on fresh cells.

Interestingly, The SOT-23 on the top for the green LEDs is a simple P-Channel MOSFET - Not a BJ Transistor… That’s why the gate resistor is only 47 Ohms - It’s not biasing current, it’s just charging up the gate.


I guess the RDSon of the FET is the current limiter then. I do not seen anything else in there to do it. That makes changing the current more difficult. FETs in that footprint are not exactly high power devices.

Where is your operating point on this curve?\_\_jCuEIpNmd3u4FHE8wCz6B6mvdHY=&docid=s8hx5ibjJELBjM&sa=X&ei=LWNHUcGEPPK04AO6vIGoDA&ved=0CDsQ9QEwAg&dur=119

Speaking of gates, I'm still waiting for the gate in my mind to open up, to this stuff. Don't think it's gonna happen any time soon, since It's getting harder to see the gate.

When all is said and done, I do not want to touch a resistor. I just did the master/slave driver setup fot the FF wannabeking and after removing those tiny things, I can't find them on my table top! I will never ever try to change one, LOL. They are smaller than Gnats, in fact they might have come off a Gnat's A.. I know my limits.

I think a nice P60 drop in is called for in this mod. So much easier on my feeble brain cells.Embarassed