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I have a two prong led that when power is supplied to it, it twinkles and changes colors.

How does that actually work? It's too cheap in my opinion to have a micro controller in the diode and it looks like a normal "radio shack" diode.

enter image description here

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    \$\begingroup\$ They add magic to the blinky ones \$\endgroup\$
    – Voltage Spike
    Commented Mar 5, 2017 at 7:02
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    \$\begingroup\$ It's not likely an MCU, more likely a simple state machine. If an MCU were used then why is it not programmable? Think how you would build a circuit to do the same thing then migrate it to custom silicon. \$\endgroup\$ Commented Mar 5, 2017 at 16:22
  • \$\begingroup\$ @Misunderstood, comparing to another led, I notice a finger print ridges on the metal, I wonder if that somehow acts to give different colors? \$\endgroup\$
    – Chris
    Commented Mar 12, 2017 at 1:41
  • \$\begingroup\$ This is a dupe of a different question: electronics.stackexchange.com/questions/30066/… and the ridges on that metal is likely for heat dissipation. More ridges = more surface area. Like heatsink fins. @chris \$\endgroup\$
    – Passerby
    Commented Mar 12, 2017 at 2:33
  • \$\begingroup\$ @Misunderstood here MCU is used as a generic term for IC/Controller/State Machine. And many many MCUs have OTP memory or fuses., so they can't be reprogrammed anyway. \$\endgroup\$
    – Passerby
    Commented Mar 12, 2017 at 2:33

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It could vary well be an MCU. It's incredible how small and cheap they can be manufactured these days.

But it doesn't necessarily have to be an MCU. There are plenty of ICs and hardware combinations of swtches that can accomplish such feats.

Imagine for example two switches with capacitive networks combined in such a way that they charge and discharge each other over some interval, thus supply the two different LED color circuits.

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    \$\begingroup\$ Micros may be cheap to manufacture but there are a few design hours needed. Those hours need to be amortized into the cost. Think about how you would design the circuit logic without a MCU. That would be cheap to make into custom silicon. \$\endgroup\$ Commented Mar 5, 2017 at 16:27
  • \$\begingroup\$ Please see the picture. There isn't a microcontroller \$\endgroup\$
    – Chris
    Commented Mar 12, 2017 at 1:33
  • \$\begingroup\$ @Chris: Atmel sells an 8bit AVR microcontroller that is 1.5x1.4 mm in size, including its connectors. The die size is even smaller. There very well could be a microcontroller in there. \$\endgroup\$ Commented Mar 12, 2017 at 2:39
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All flashing RGB leds have a microcontroller inside. (Some older) Blinking single color leds have a bi metallic strip that flex when it heats up to break the connection then flex back when it cools to turn back on. Newer or more complicated ones do not. I have some single color "flickering"/"candle" leds that do not have a steady pattern.

5mm LED with IC. That Black box is the microcontroller. enter image description here

This one you can see multiple bond wires, likely being a RGB led. enter image description here

5050 smd LED with a smart controller. enter image description here

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    \$\begingroup\$ Bi-metal strip inside blinking led? Surely you're joking? \$\endgroup\$ Commented Mar 5, 2017 at 10:03
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    \$\begingroup\$ I'm not buying the metallic strip story either, it may be true, I'd have to see proof. \$\endgroup\$
    – Voltage Spike
    Commented Mar 8, 2017 at 5:15
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    \$\begingroup\$ @user1890202: LEDs have been in use since the 60's. It's quite possible. \$\endgroup\$ Commented Mar 12, 2017 at 2:44
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    \$\begingroup\$ @Passerby or should I call you Shirley? Shirley you are joking, again. To call a WS2811 smart is a stretch. It's a programmable latch and dims the RG&B based on the latched value. And the IC is not embedded in the LED. The WS2811 case is the size of a 5050 LED. The image you said likely being an RGB is single color with a wire bonded 1.5hz flasher. I do not see the single color bimetallic strip. How would a bimetallic strip move when encapsulated? The one with the black box "microcontroller" is an RGB sequencer. Smart? MCU? I don't think so. IC? shirley. An IC in MOST 5mm LEDs??? \$\endgroup\$ Commented Mar 12, 2017 at 11:09
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    \$\begingroup\$ @whatsisname How does the LED being around since the 60s have any relevance? It would be a bad idea to put a bimetallic switch in an LED no matter what year. Think about the precision that would be required to make a tiny bimetallic strip. Think about the minimal temperature differential of the typical 5mm LED. Think about the ambient temperature's affect, like on indoor outdoor xmas blinking LEDs. What would the blink rate be? At what temperature would it switch? The tiny precision strip would need to be very carefully ($) enclosed in a case otherwise it would be encapsulated in plastic. \$\endgroup\$ Commented Mar 12, 2017 at 11:43
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It's too cheap in my opinion to have a micro controller in the diode

You'd be surprised how cheap it can be to manufacture a MCU that small in that quantity. So yes, there is a MCU in the package.

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    \$\begingroup\$ Do you really need an MCU to do a couple of simple functions? Silicon cost is based on how many chips per waffer. If you did a logic circuit to accomplish the same functions do you think that would take more or less silicon real estate than an MCU? \$\endgroup\$ Commented Mar 5, 2017 at 16:30
  • \$\begingroup\$ Please see the picture. There isn't a microcontroller \$\endgroup\$
    – Chris
    Commented Mar 12, 2017 at 1:33
  • \$\begingroup\$ @Misunderstood: depending on volume, it may easily be cheaper to use something else off the shelf than to spend the time dealing with it yourself, even if it is somewhat overpowered. \$\endgroup\$ Commented Mar 12, 2017 at 2:41
  • \$\begingroup\$ @whatsisname it's always cheaper to by micros off the shelf. OP said "cheap to manufacture". Do you think? A micro controller to make an LED twinkle? If you were asked to design a simple twinkle circuit, that's the best design you can come up with? Where is the power supply? \$\endgroup\$ Commented Mar 12, 2017 at 9:54

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