From the internal circuit diagram of the NE555 you can see that the output pin 5 (CTRL) is directly connected to the point A.
Internal circuit diagram of NE555 with CONTROL output. |
Measuring the voltage between Pin 5 (CTRL) and Pin 1 (GND), shows you indeed V = 6 V on your multimeter, or rather 2/3 Vcc.
This voltage is referred to as the reference voltage of the NE555.
Circuit diagram measurement of the reference voltage at the CTRL output. |
Circuit measurement of the reference voltage at the CTRL output. (Enlarge) |
In almost all practical circuits the CTRL output is connected to GND using a capacitor. This serves to stabilize the reference voltage and to filter out spikes...
Circuit diagram NE555 with a connected CONTROL output. |
Circuit NE555 with a connected CONTROL output. (Enlarge) |
In the next step you get to know the OUT output.
