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Reducing brightness of LED bulb

BadRequest

Oct 28, 2022
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I have this LED light bulb with built-in PIR sensor. It uses a BIS0001 chip which is common on PIR modules and I was able to extend the time on by swapping the 100K timing resistor R2 for a 910K (what I had on hand). I guess it's a long shot but I was wondering whether anyone reckons there could be a simple way to reduce the LED brightness as well? I tried several different resistors but 75R and above makes the bulb flicker rapidly.

The voltage across the LEDs is about 37 V and they are arranged in 12 series sets of parallel pairs (so 24 total with just over 3 V across each parallel pair). I'm not entirely certain what current is flowing but I think it's in excess of 200 mA. When I tried a 47 ohm resistor in series, the voltage across it was 10 V so I removed it again (it was only rated for 1 W).

Thanks.
 

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Bluejets

Oct 5, 2014
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simple way to reduce the LED brightness
Install an LED dimmer of the appropriate type.
Note that all dimmers do not suit.
That is of course if it is a dimmable LED fitting, otherwise all you will get is flickering as you have already experienced.
In that instance get an LED dimmer of appropriate type and an LED fitting to suit.
 
Last edited:

Sunnysky

Jul 15, 2016
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It will be difficult to find the current sensing resistor for this constant current source. However if you find a resistor with the constant voltage drop used for current sensing, by increasing the resistor value of that current sense you can reduce the current
 

BadRequest

Oct 28, 2022
2
Joined
Oct 28, 2022
Messages
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It will be difficult to find the current sensing resistor for this constant current source. However if you find a resistor with the constant voltage drop used for current sensing, by increasing the resistor value of that current sense you can reduce the current
Indeed, the power supply in the base of the bulb had a chip (BP3125) with two resistors in parallel which set the current (1R1 and 5R6). I removed the lowest value resistor and this gives a much dimmer and cooler-running bulb. Thanks.
 

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