I ordered these from an Amazon seller, Liroyal-led, a few weeks ago in April. It took that long to ship from Hong Kong. They are 50 pcs of Bluecell 5mm RGB full multicolor flashing LEDs. The cost was $3.45 including free shipping.
The case is clear epoxy. I looked down inside and saw four chips wired together. Three of these are the LEDs and then there’s the 4th chip, which is much larger then the LEDs. I can see fine patterns on the chip so it may be a microcontroller. It flashes the LEDs at first a slow and then a fast pattern. The colors change during each fast or slow period.
To test one out, I connected one to a power supply. It began to flash as I described above. But the voltage was critical. If I increased it slightly the current increased a lot, which indicated to me that these LEDs need a current limiting resistor in series, to prevent the current from becoming excessive.
I connected the LED to a Joule Thief. Because the JT output was pulsating, the LED put out all three colors and did not flash. I connected a 1N4148 Diode and 47uF capacitor to the output, to rectify and filter out the pulses. The LED was directly across the capacitor. The LED began blinking as it was supposed to, and changed colors. The JT supply current varied between 75 to 80 milliamps, which is about normal.
These LEDs add an interesting effect, but require DC to work properly. I think the best way to use them is to put a 100 ohm resistor in series and connect them to a 5 volt DC source, such as a USB charger. An old USB plug will allow them to be plugged into any 5V power source. But use only the Red and Black wires.
