Here is a 555 timer simulation, the output is adjustable duty cycle (less than 50%), the previous simulation, but this simulation is wrong...

chuzhaonan

Here is a 555 timer simulation, the output is adjustable duty cycle (less than 50%), the previous simulation, but this simulation is wrong... [Copy link]

Here is a 555 timer simulation, the output is adjustable duty cycle (less than 50%), the previous simulation, but this simulation is wrong, who can guide me? ? ? ?

captzs

  In the circuit below, when the potentiometer slides, the resistance at both ends changes by the same amount, so the capacitance charging and discharging time increases and decreases by the same amount, the frequency remains unchanged, but the duty cycle changes. The resistance value of the potentiometer is determined by the frequency.

chuzhaonan

captzs posted on 2019-4-25 20:02 In the circuit below, when the potentiometer slides, the resistance at both ends changes by the same amount, so the capacitance charging and discharging time increases and decreases by the same amount, the frequency remains unchanged, but the duty cycle changes. Electric...

What is the formula for calculating the frequency and duty cycle of this?

qwqwqw2088

The circuit parameters on the first floor seem to be wrong. Can it produce a square wave?

qwqwqw2088

Please refer to the following

chuzhaonan

qwqwqw2088 posted on 2019-4-27 17:29 Please refer to the following

I want to make a 20K, 30% duty cycle square wave, how to calculate it?

qwqwqw2088

chuzhaonan posted on 2019-4-28 09:42 I want to make a 20K, 30% duty cycle square wave, how to calculate it?

There are NE555 oscillation calculations on the Internet

qwqwqw2088

T＝0.693（R1＋2R2）C or f＝1.44/[(R1+2R2)*C]. If you want to keep the frequency constant and only change the duty cycle, you can select C, keep R1+2R2 constant, and change the R1/R2 ratio. The larger the R1/R2 ratio, the smaller the duty cycle, and vice versa. If you want to change the frequency and fix the duty cycle, you can select C, keep the R1/R2 ratio constant, and change R1+2R2.