After it is triggered, it will eventually return to its stable state, which makes it really handy as a programmable timing circuit. All of this can be accomplished in the astable circuit with a pair of transistors, two capacitors, and four resistors -discrete components that only the very very nerdy, old-style Radio Shack types cough have squirreled away in their garages and shops in neat rows of little plastic bins.
The first vacuum tube multivibrator circuit was completed in by radio and electronics pioneer William H. Eccles and his trusty side-kick Frank Jordan. Jordan is relegated to the mists of obscurity.
Your garden variety Spookyfire Blob flashing LED has built into it a tiny little astable multivibrator circuit. If these components vary in the least bit from one circuit to another or one LED to another , their frequency relative to one another will be slightly different. Blame F. This circuit is from my Free Email Course on how to make a light blink. An inverter is a logical component that outputs the opposite of what it gets in.
If it gets a high voltage in, it gives a low voltage out. And vice versa. A high voltage is a voltage close to the supply voltage. A low voltage is a voltage close to zero volts. In the circuit diagram you can see that the output of the inverter U1 is connected back to the input with a resistor. But since the output is connected back to the input, the input will be low. Now that the input is low, the output will be high. That means the input will be high again, and so on….
The resistor R1 controls how much current that goes back to charge the capacitor on the input. One can easily fit into an LED. I don't have any, and there's likely only one method used. Here's a link with a data sheet, just says IC is involved. I was hoping someone had intimate knowledge of what the IC entails. Maybe someone with these and an oscope could describe what it looks like in a circuit- normal LED behavior of constant voltage drop or perhaps an open circuit during off-times.
There will be someone, working for a semiconductor company, probably in the Far East, probably under a non-disclosure agreement. And remember every LED company will have their own take on this, its a highly competitive market. A couple of "candle flicker" LEDs have been reverse engineered, as described here. The device consists of two chips, the actual LED and a fairly simple controller. Lately, some solar powered garden lights have come on the market that have multicolor LEDs and controllers that change color and brightness in a long term pattern.
Those have some simple microprocessor built in to the LED housing. Thank you for that link, jr.
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