Firefly Jar

Description

These were gifts I made for friends and family. I'm calling it the Firefly Jar since it looks like a jar of invisible flickering fireflies at night.

This project is a replacement lid for a mason jar. The PCB is 2.5 in diameter with a 55 mm round solar cell on top. This centers perfectly with a standard mason jar and lid collar. The solar cell recharges two 1.2V Ni-MH AAA batteries during the day. At night a P channel MOSFET switches on two candle flicker yellow LED's through a 2.1V LDO voltage regulator. The MOSFET only engages the LED's when the voltage on the solar cell is low and the batteries are above their 0.85V empty state. The LDO voltage regulator is an easy way to ensure a constant LED brightness throughout the life of the batteries.

This would make a good DIY kit since the part count is minimal and all components are through hole.

See a gif of the Firefly Jar here.

See a video of the Firefly Jar in action here.

Components

1 × 5V 400mA solar cell Adafruit PRODUCT ID: 700

1 × blocking diode 1N5817DICT-ND

1 × P channel MOSFET TP0604N3-G-ND

1 × DPDT switch 401-2001-ND

2 × candle flicker LED BL-L513UYC-B-S3

Discussions

megan wrote 11/07/2016 at 05:49

Hmmm... i was interested in building this. Is the schematic no longer available? Thanks.

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ourlibrary2011 wrote 02/27/2016 at 15:20

Is there a schematic for this project ! .

cheers

spike

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knoxfis wrote 02/02/2016 at 22:28

Just wondering if you found that the caps were necessary after not using them and if so was the value intended .1 or 1 uf. Thanks.

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Alexandre Bury wrote 01/15/2016 at 05:02

Great project!

Small question: how did you connect the solar cell to the PCB? There's no pin, just solder pads.

Thanks!

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Emach00 wrote 01/11/2016 at 19:44

In volume how much would one of these go for?

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alkhaarj wrote 01/10/2016 at 20:01

why do you have two DPDT switches in the schematic? Am I missing something?

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luisestrada115 wrote 01/11/2016 at 17:12

wondering the same thing, BOM only has one.

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Michael Mogenson wrote 01/11/2016 at 18:58

the schematic component has two parts. one switch connects/disconnects solar cell to batteries and batteries to MOSFET.

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alleybeachelectric wrote 01/10/2016 at 02:09

looks great! can I ask, why did you not populate the capacitors on your board?

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Michael Mogenson wrote 01/10/2016 at 03:16

because I forgot to order them

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Markus wrote 01/09/2016 at 12:18

Hey,

nice project. Where do you get those jars and these lids? They aren't this common here in Europe.

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Michael Mogenson wrote 01/10/2016 at 03:18

Ball Canning Regular Mouth Half Pint Canning Jar 8 oz. 12-Count https://www.amazon.com/dp/B00HNPNNLS/ref=cm_sw_r_cp_awd_O1CKwbDJK4TSB

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Firefly Jar

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