555 timer pulsing alternate LEDs.

142

00:52:50

Free-running 555 timer pulsing one of two LEDs alternately. Uses DFF (configured as TFF) and NAND gates.

published 4 years ago

cjdelphi

4 years ago

the 555 sources and sinks, meaning connect an led directly to pin 3 via a resistor and do it again with the led in reverse... lol

HIGreg

4 years ago

Good point. I noticed the 555 ouput wasn't full rail so a buffer seemed prudent to meet DFF digital logic levels, my chosen DFF part output can't sink or source sufficient current, the LED on time and off time isn't separately controllable nor identical for both LEDs without the gates.

HIGreg

4 years ago

I modified to your suggestion, but without the NAND gate as buffers, the simulation fails after a few cycles. Also, in my use case, the LEDs will be separated by a long wire (about a meter), so I didn't want that to add to the resistance for that LED.

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