Maker Factory ELECTRONICS EXPERIMENTS BOX Manual page 250

Circuit 26 – 28: Electrolytic capacitor C1 charges fully, when button S1 is activated. R2 and R3 are used to
discharge the e-cap. For as long as the capacitor voltage remains above the threshold voltage of the transis-
tors, T1 and T2 remain switched through and LED1 is lit. If the electrolytic voltage drops below the value of
the threshold voltage, the transistors block, LED1 turns off.
252
Fig. 3.25: Circuit
25: Automatic
solar light with
battery
Fig. 3.26: Circuit
26: 2 seconds
switch-off delay