arc aaa purpose of capacitor across led leads

Gt390

Newly Enlightened
Joined
Oct 4, 2016
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118
Hi, I hope this is the correct forum for this question. I am in the process of upgrading the led in an old arc aaa flashlight. I have been looking at the driver while waiting for the new led. One thing I am wondering about is the function of what appears to be a capacitor soldered across the leads of the led. Is this to limit current or smooth out voltage spikes from the driver? Excuse me if this is an ignorant question but I am wondering if leaving it off will increase brightness at the expense of runtime. Or cause some other unwanted effect.
Dan
 

calipsoii

Flashlight Enthusiast
Joined
Apr 21, 2010
Messages
1,412
I'd leave it there Dan. Most boost converters require an output capacitor for normal operation. You are correct that it smooths the voltage output to the LED but it also serves the important purpose of smoothing the feedback voltage to the boost chip. Without a capacitor, most boost chips cannot accurately read their own output voltage and so they don't function correctly.

To increase output you could do a couple things:
  • Change the sense resistor (if the circuit has one)
  • Use an LED with a lower forward voltage

Best of luck!
 

Gt390

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Joined
Oct 4, 2016
Messages
118
Thank you very much. That makes sense even with my limited understanding. I will leave it alone. You obviously know what you are talking about , do you do much modding yourself?
 

Gt390

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Oct 4, 2016
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118
Holy smokes, yes archemides I would say he does. Some very clever people on this forum.
 
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