Convert this multimode light to a single mode?

cuvy

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Wondering if anyone can suggest a simple way to convert a 3 sequential mode light into a single mode.

I bought these spotlights for my motorbike, but they're three mode - cycles between high, low and strobe each time power is switched off and on (doesn't require momentary press). Just the high mode is all I need for these lights. Does anyone know if there's a simple way (for example, removing some of the components on the board) to remove the modes?

I'm hoping maybe it's a standard circuit that someone recognised and knows how to convert mode behaviour?

IMG_1786.jpeg
 

cuvy

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Sorry, meant to post this in "Homemade and Modified Flashlights Discussion" but can't seem to move or delete the thread
 

Dave_H

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Good image, at least we have some specifics to look at.

Looks like an older design by the pill style of LEDs. It's probably a 3-series/2-parallel LED configuration with single switching step-down converter (8 pin SOIC). I don't recognize the chip and can't find data on it so far (sometimes a datasheet is useful).

Of all the 12v "auxiliary" LED lights I've acquired so far, all have been single brightness level only, so yours is more of an exception (wondering why they did this?).

Dave
 

cuvy

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Australia
Yes this is the first multimode light like this I've encountered. It came from eBay, so i guess some chinese designer thought multimode would be a good thing and included it?

I'm not very well versed in how the driver circuits work, but i was hoping there would be common driver ICs which use signals on pins to control mode behaviour (eg pin X tied to VCC to enable strobe, etc), and perhaps resistor/capacitor combinations to control PWM output frequencies (for brightness or strobe speed). The 8 pin SOIC ("1053B C12A 044271") as you pointed at seems like the one, but I'm not having any luck either on finding a data sheet for it.

I will see if I can reverse engineer a schematic for it by tracing the wires and see if that makes any more sense.
 

Dave_H

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Typical drivers used on 12v/24v I find are buck (down) converters up to 1A or more at 30v, some in very small SOT package with thermal pad. PT4115E is common. Control is typically one pin for on/off (pulled up to 5v internally) also used for PWM and may accept analog dimming 0-5v. Not sure about the SOIC-8 package, may use a bottom thermal pad soldered to board (just in case you want to remove it).

What happens when you reduce voltage below 12v (if possible with variable PSU)? If they are 3S, you would see gradual dimming below 10-11v, falling off faster below 9v. Most chips have low-voltage shutdown around 5-6v but LEDs would be off by that time; would only affect 2S (could be 2S3P, three parallel groups).

As for bypassing mode switching there has been discussion if flashlight forums about this; possibly using capacitor to hold the mode state, but too early to tell if this applies here.

Dave
 

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