**broken link removed**
Can someone please help me understand how these work.
In the first one the diode zener and 100k create a voltage of 3.3v. The voltage on the the 200ohm resistor is 3.3-0.7v (0.7v -voltage on the transistor)
Ie=Ic so that the elec current on the capasitor is 2.6v/200ohm.
The cap is charged and when it reaches 2/3Vcc it discharges (because of the transistor in leg 7 of the 555 timer). When it reaches 1/3 Vcc it is charged again and the same thing is repeated. So what do you get for the output of the 555 timer. Usually the trigger is a seperate pulse but this time it's connected to the 6th and 7th legs. Also how do I calculate the time of the output pulse t=r*c?
In the second one it looks like the same thing except without the diode zener. What is the function of the opamp at the bottom?
Can someone please help me understand how these work.
In the first one the diode zener and 100k create a voltage of 3.3v. The voltage on the the 200ohm resistor is 3.3-0.7v (0.7v -voltage on the transistor)
Ie=Ic so that the elec current on the capasitor is 2.6v/200ohm.
The cap is charged and when it reaches 2/3Vcc it discharges (because of the transistor in leg 7 of the 555 timer). When it reaches 1/3 Vcc it is charged again and the same thing is repeated. So what do you get for the output of the 555 timer. Usually the trigger is a seperate pulse but this time it's connected to the 6th and 7th legs. Also how do I calculate the time of the output pulse t=r*c?
In the second one it looks like the same thing except without the diode zener. What is the function of the opamp at the bottom?