This simple strobe light is from an article in 1982. Its complete circuit, very simple, appears in the figure. In this circuit, the relaxation oscillator, with the 2N2646 unijunction transistor, produces the power stage firing pulses that carry a type 106 SCR (MCR 106-4 or MCR106-6). The frequency is given both by the capacitor C1 and by the position of the adjustment that is made by a potentiometer. For the oscillating step with unijunction transistor the author of the project used a separate source consisting of a 6 V battery (4 batteries connected in series). As the consumption of the oscillating stage is quite low, the battery life will be great. The power stage is powered by the 110 V or 220 V local network, being able to control lamps of up to 100 W. For lamps from 60 to 100 W, it will be convenient to mount the SCR on a heat sink. For smaller lamps you will not need the heatsink. Note that the maximum frequency of the oscillator is determined by the inertia of the common lamp that cannot go beyond a few Hertz.
