Solar powered 2 pin RGB LED

[Lucky-Luka]

Hi all
I have an RGB LED led that needs more or less 3 volts to perform correctly its light routine.
Can I use for my project a 3.3V zener diode?
Only using the rectifier diode and the cap as a buffer the voltage would be a rather constant 4.8V.
Cheers

 

[Nigel Goodwin]

Most likely not, LED's are current driven not voltage driven - you need more than it's specified voltage and limit the current it takes. As a minimum, and if the supply voltage is constant, then a simple resistor (calculated with ohms law) is all that's needed.

 

[Lucky-Luka]

I forgot that LEDs are current driven. I've modified the circuit and it works just fine now. I've used a schottky diode for more luminosity. The LED draw 10mA more or less. Where would you put an ON/OFF switch?

 

[audioguru]

The high current zener diode you selected needs 76mA!!
The datasheet for the QX5252 shows the circuit without a zener diode since an LED or a colors-changing LED limits the voltage.
The datasheet shows that your circuit's 47uH inductor limits the current to fairly high 75mA pulses when the battery is 1.3V. I have many solar garden lights using the QX5252 IC and most use a 82uH inductor. A few use a 47uH inductor, are brighter and last for years.

Your multimeter probably cannot accurately measure the average current of the high frequency poorly filtered pulses., and the activity of your colors-changing LED might slowly dim or pulse the LEDs.