Add a low power indicator LED

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jack0987

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I have some small battery powered Arduino sensors in plastic cases about the house.

My thinking is I would like to drill a small hole and put an led behind it to add a small indicator led to each so when I look up at them and the led is lit I know the battery is not dead yet.

The Arduino runs on low power and only wakes up on an interrupt. With a T5 led ran for about 10 days. The Arduino has an led and so far it has run 90 days.

Perhaps size matters.

Please suggest some ideas. low cost is best.

Edit: Changed thread Title
 
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Thanks. I did spot that 5mm one now, but there is a 3mm version which I would prefer. High light level is not as important to me. As long as I can see it is all that matters.
 
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jack0987 said:
High light level is not as important to me.
Click to expand...

High light output for a given current means LESS current to get the SAME light.

I have some ultra-bright LEDs that are as bright as basic LEDs such as used for "power on" indicators with just a few microamps current, rather than milliamps.

[I was going to suggest them at the start of this thread, but the exact type I have i no longer available).
 
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jack0987 said:
Thanks. I did spot that 5mm one now, but there is a 3mm version which I would prefer. High light level is not as important to me. As long as I can see it is all that matters.
Click to expand...
Yes, but the higher light level for a given current means you can reduce the duty cycle to almost nothing and get an acceptable result that won't drain your battery. You need to start playing 3-D Chess.
 
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I am wondering if the type mounted on circuit boards may take much less power.
Here is a not so good picture of what I mean.

Being so small, they will be a challenge for me to work with.
What do you think?
 
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Papabravo said:
Yes, but the higher light level for a given current means you can reduce the duty cycle to almost nothing and get an acceptable result that won't drain your battery. You need to start playing 3-D Chess.
Click to expand...

Playing 3-D chess?

I did get in some 3mm dome leds and they say 2mA. They are surprisingly quite bright. Much, much brighter than I would like.

How does one reduce the duty cycle?
 
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jack0987 said:
Playing 3-D chess?

I did get in some 3mm dome leds and they say 2mA. They are surprisingly quite bright. Much, much brighter than I would like.

How does one reduce the duty cycle?
Click to expand...

Create your duty cycle by coding it to turn on the LED for X milliseconds and off for Y milliseconds. The X being your duty cycle. X+Y=period of signal. And just loop that whole sequence for however long you need. Adjust X and Y until you hit your sweet spot.
 
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jack0987 said:
I just drilled a much smaller hole for it to shine through.
Question: Would a higher value resistor reduce it's power consumption?
Click to expand...
Yes, of course, simply apply ohms law - however, less current means less brightness - much of this thread has been about increasing the resistor to reduce current (and brightness).
 
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I feel certain, in the end, I will be doing as you suggested once I take the time to study it. LOL
 
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