With an NE555 you are also able to build an astable multivibrator or blinker. Find out how, and what you need to be aware of.

Consider the circuit shown.
You surely recognize the circuit of the **Experiment 9**,
now with a capacitor **C1** of **larger capacity**.

When you take the circuit into operation,
the **LEDs** light up **alternately**.
Thereby **LED2** lights up about twice as long as **LED1**.

You can calculate the **switching times** approximately.
The time **τ _{1}**,
in which

τ_{1} = 0.7 × (R_{1} + R_{2}) × C_{1}

= 0.7 × (47 000 Ω + 47 000 Ω) × 0.0001 F = 6.5 sec

The time **τ _{2}**,
in which

τ_{2} = 0.7 × R_{2} × C_{1}

= 0.7 × 47 000 Ω × 0.0001 F = 3.3 sec

The **oscillation t** is calculated as the sum of
**τ _{1}** and

t = τ_{1} + τ_{2}

= (6.5 + 3.3) sec = 9.8 sec

and the **frequency** **f**...

f = 1 / t = 1 / (τ_{1} + τ_{2})

= 1 / 9.8 sec = 0.1 Hertz

From the formulas you will certainly understand
why the **LED2** lights up twice as long as **LED1**.
The capacitor is **charged**
via the resistors **R1** and **R2**,
but **discharged** via the resistor **R2**.

In the next experiments, you play with the switching times ...