Full of stars

I thought it would be good to flash some LED's.

I wanted either red or white LED's flashing from a 2 or 3 volt source.  White LED's would require some boosting while red LED's would run quite happily down below 2V.

I put this together at lunch time to prove the idea and adjust flash rates...

The 74HC14 is spec'd down to 2V, I ran the thing from about 2.5V.  The LED I used was a random white LED.  With the components shown the flash rate was a few tens of ms on and a few seconds off.  C2 is used to boost the voltage across the LED.

That works ok, now I need to switch it on/off depending on ambient light....

Swapping the 74HC14 for 74HC132 makes this a bit easier.

Adding a simple 'dark' detector (Q1, D3 & R5) switches the flashing off during the day.  While 'off' current draw is below 10uA.