I know there are many questions about LED blinkers, but I haven't yet found a clear answer for this.
I have a 555 circuit blinking a blue led (or three in parallel). I has a low duty cycle (using a diode between pins 6 and 7).
It works fine (blinks the LED without resistor, giving a very bright light) when powered off a USB 5V source, but I have no clue as to what the power consumption is.
I want to transfer this design so it can run on batteries for many hours as a beacon (at least for weeks) (I will add a magnetic switch so it can be waterproof). I need it to last as many hours as possible, without much bulk. Is this circuit moderately efficient for that purpose?
Clarification : It will be used as a beacon, off for 1-1.5 seconds, then on for a very short time. No accurate timing required. It is working as described now with the only difference being that the 20k resistor is in fact a 10k plus a 10k pot to play with the timing while prototyping.