PUT LED flasher V2

The next circuit is based on the PUT symmetrical square wave generator to make a LED flasher, that generates a very bright flash approximately every second.
At first sight, the LED seems to be the connected upside down. But it is connected correctly. This is because in the way, we use C2 and D2 to generate a voltage at node 3 that rises above the power supply voltage.
We want to generate a flash at the moment that node 2 pulled up to the supply rail by Q2 at the moment that the PUT latches into conduction.
When Q2 is not conducting, C2 will be charged via D2 and R2.
When Q2 starts conducting, node 2 will be pulled up to the supply rail, while C2 is charged. So at the first instant, the voltage on node 3 will be the power supply voltage plus the voltage over C2.
This means that the LED is forward biased and C2 will now discharge rapidly through the LED that starts conducting. Due to the instantaneous high discharge current, that is proportional to the size of C2 and the voltage over C2, the LED will show a bright flash.
The timing of the circuit depends on the power supply voltage. So when changing the power supply, the frequency of the flashes will change.
When you want to adjust the frequency of the flashes, the easiest way is to change the value C1. When changing resistors to change the frequency, this will also change the bias currents for the transistors. When these currents are too low, the PUT does not latch firmly or does not unlatch, causing the oscillator to stall or to not start at all.
C2 can be increased to 220uF or 470uF to increase the discharge current of C2 through the LED, causing even more bright flashes.