Hack a Y4839A-15 Dollar Store Headlamp LED

I created a simple circuit (based on an ATTiny85) that strobes an LED based on a reading from a pot. The LED I used worked fine, but it was not very bright. I started sourcing brighter LEDs on AliExpress as replacements. However, today in the Dollar Tree store, I found a strap on headlamp with a fairly bright CoB LED. I thought there has to be a way to use this in my strobe, so I bought it.

The headlamp had a push button that cycled through OFF-ON-DIM-STROBE settings, which was not ideal for my application. It took me a while but I figured out how to bypass the button and circuit.

1. Y4839A-15 Headlamp
2. a very small piece of wire
3. soldering tool
4. 3 AAA or AA batteries with battery pack

There were no markings on the IC, so it took me a minute to figure out what was going on. There is a test point above the LED array that seems to be the anode. Running a jumper from that test point to the resistor bypassed all the circuitry. As long as there is power, the array is lit.

With the test complete, I removed the module from the battery case. Shown here is a decent look at the PCB traces on the back side.

Here is a photo of the LED lit by three AA batteries. The original headlamp used 3 AAA batteries. It is fairly bright.

Finally, I removed the IC chip (does anyone know what that is -- see blue arrow), the momentary on button, and the 1R5 resistor.

For just over a dollar (no shipping), I have a fairly bright LED panel.