So a few years ago I put together this 555 timer circuit that I was using to flash some LEDs. In my eagle schematic it says it flashes about once per second. See attached eagle schematic. I cannot seem to find any other documentation I saved as to why it works... but I still have the PCBs and they work.
Now looking at some of the typical astable circuits online and in the datasheet there are some clear differences.
Hoping someone can help me understand my old circuit as I can't seem to piece it together in my head anymore.
Thank you,
EDIT: Just to add to this thread... my goal was re-use the circuit to drive the gate of an N channel mosfet so I could control higher power LEDs. The flash rate is suitable for what I want but I'd like to understand how/why this is different than the typical 555 led flasher circuit.
Note that if you used the bipolar NE555, it probably won't flash at the same frequency and duty cycle, predicted by the simulator, which will assume the output stage swings over the full supply voltage range. In reality, the 555 has an asymmetrical output stage, with slightly more voltage drop on the positive, than the negative side, which will cause the capacitor to charge more slowly, than discharge.
Awhile ago, I made a detailed LTSpice model of the 555 timer's output stage. Here it is connected as a Schmitt trigger. It should have a duty cycle of 50%, but it's higher than that, because the output stage saturates at 1V to 1.4V below the supply, depending on the current, when its positive.