I am an electronics technology student. I am looking at an astable multivibrator. Pin 5 is normally grounded, but in this case it is not connected to anything. One of the questions of my homework is "why or why not the pin 5 configuration would be correct".
Also another thing I'm having trouble with is that it's asking me to find PW (Pulse Width) when VCC is at 20 V, but I know that 555 timers can only operate up to 15V and 18V if it's a military timer. So what would be my pulse width?
In an astable multivibrator, why might I not connect pin 5 to anything?
- Posted:
- 3+ months ago by elwebbr23
- Topics:
- grounded, case, student, technology, pin, electronic, connect, electronics
Details:
Answers (1)
Inside the 555 timer is a voltage divider the divides +VCC into thirds. A voltage comparator compares the trigger input (pin 2) with 1/3 VCC, and another comparator compares the threshold (pin 6) with 2/3 VCC. The point at 2/3 VCC on the voltage divider is connected to the control voltage (pin 5). This pin can be used to modify the values of 1/3 VCC and 2/3 VCC without having to change VCC. However, if this input is not going to be used, it should be grounded through a bypass capacitor (0.01uF) to protect it from noise.
hades.mech.northwestern.edu/index.php/555_Timer
Vcc at 20V makes no sense.
You can download a data sheet from several sources here: www.google.com/search?q=LM555+data+sheet