Firefly Jar

[spike47]

Hi

I am wanting to a make a Firefly Jar , I found the project on american site , I just wanted to know if anyone on here can help me with making it and sourcing the items info as follows .

This is the info from the web site , I will attach a drawing ! :

DESCRIPTION: 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.

Cheers

spike

 

[DerStrom8]

Hi Spike,

Could you post a link to the project page?

If you can provide a specific list of the parts you need, we can help you figure out where to obtain the parts.

Regards,
Matt

 

[spike47]

Hi Spike,

Could you post a link to the project page?

If you can provide a specific list of the parts you need, we can help you figure out where to obtain the parts.

Regards,
Matt

Hi

Thanks for your reply , Here is the link , https://hackaday.com/2016/01/07/simple-solar-mason-jar-lights/

ps: not sure if this link is the same info as my first post ! .
cheers

spike

 

[spike47]

Hi Spike,

Could you post a link to the project page?

If you can provide a specific list of the parts you need, we can help you figure out where to obtain the parts.

Regards,
Matt

I am in the UK !

 

[DerStrom8]

I am in the UK !

That doesn't really answer my question....?

 

[spike47]

H

That doesn't really answer my question....?

Hi

Sorry that was supposed to go with my last answer ,here is the full list as a pdf file

 

[audioguru]

There is no current limiting to prevent the LEDs from burning out.

 

[spike47]

There is no current limiting to prevent the LEDs from burning out.

Hi

Thanks for your reply , can something be incorporated that would solve that ! .

 

[audioguru]

You posted no datasheets:
1) The Evil Mad Scientist flickering LED lists it as 30mA, 2.1V as typical but does not list the range of voltage.
2) The datasheet is in Chinese so I needed to load an Extended Asian Pack in Adobe.
3) The datasheet says that the LED absolute maximum allowed current is 30mA and shows a graph of its typical voltage vs current. It is 2.1V at 15mA and it also does not show a range of voltage and does not show the minimum voltage.

The voltage regulator maximum output current is 200mA which will blow up the LEDs if their voltage is low and the regulator's voltage is high. If the LED voltage is high and the regulator's voltage is low then the LEDs will not light.
Therefore you are gambling with the simple circuit.

I would use a resistor in series with each LED to limits its current. Try 16 ohms then it will limit the current to 25mA with a voltage drop of 0.4V. Then if the LED voltage is low at 1.8V and the regulator's voltage is high at 2.2V the LEDs will not burn out.

 

[spike47]

Hi
Thanks for your replies , will this Schematic attached help !

 

[audioguru]

You can add the current limiting resistors to your PDF schematic yourself. I find that in a PNG schematic it is much easier to add parts.
I also notice that some TP0604 Mosfets will turn off too soon when the battery voltage has dropped to 2.6V or 2.7V when it still has plenty of charge because of the "range" of Vgs(th) when it conducts only 1mA.