This is a LED strobe circuit powered by two sources AC and DC.
OPERATION
The SPDT switch at the top turns off the strobe while the one at the bottom increases the rate of the strobe when switched off.
The red LED indicates that the circuit is functional.
The diode is placed in a forward biased position so as to rectify the current passing through it.That explains why the red LED doesn't flash.
The first NPN transistor increases or boosts the electric signal coming from the AC source connected to it and passes it to the second transistor which also does same, therefore the strobe effect is produced.
The brightness of the strobe is influenced by the resistors at the lower parts of the circuit and the capacitor.
