What does the discharge transistor do in a 555 timer circuit?
Transistors are like that for electronics. All digital electronics are made of transistors. When the line labelled control goes high, the transistor turns on and connects the circuit it’s connected to, to ground. In the 555 this is used as the mechanism to discharge the timing capacitor.
What is the role of transistor connected in the internal circuit in 555 timer IC?
This transistor saturates or cuts-off according to the output state of the flip-flop. The saturated transistor provides a discharge path to a capacitor connected externally. Base of another transistor is connected to a reset terminal. A pulse applied to this terminal resets the whole timer irrespective of any input.
What does the discharge transistor do in the 555 timer circuit?
Question is : What does the discharge transistor do in the 555 timer circuit? , Options is : 1. discharge the external capacitor to stop the timing, 2. charge the external capacitor to stop the timing, 3.charge the external capacitor to start the timing over again, 4. discharge the external capacitor to start the timing over again, 5. NULL
Can a 555 capacitor be used as a discharge pin?
Note: Using the discharge pin may not work, since the 555 is unpowered, the state of the discharge transistor is undefined. You will still have a slight variation on second firing due to the diode drops though. Using shotky diodes would help, but watch out for the leakage currents on those.
How does a 555 timing capacitor power itself?
When you close the switch it powers the 555 which in turn drives its output high, pulling in the relay to keep itself powered when you let go the button. After the timeout the relay is released. As you have discovered there is no actual discharge path for the capacitor.
Why does the 555 draw so much current?
Normally (when the 555 is permanently powered via its Vcc pin) the THRESHOLD pin doesn’t draw any considerable amount of current even if the timer has expired, so I doubt that this high discharge current would be due to normal BJT BE current to keep the transistor open.