This is a 555 IC in the Astable configuration it will give off a square-wave form with a frequency ) The capacitor (C) is charged through resistor (R1+R2) and discharges through R2 only.
( C is in Farads & R are in ohms )
To build a astable 555 with +/- 1Hz period and 50% Duty cycle you will need:
555 IC, R1-10k, R2-150k, C-4.7uF, C1-10nF (103)
All this can be bought at Maplin Electronics