- #1
icculus723
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i am trying to design a switch that will output an active high if the width of the received PWM signal is greater then 1500 uS. if it is shorter then this time then it should output an active low. The frequency of this signal is 50 Hz.
I designed a RC circuit with a cutoff frequency of 50 hz, and found a threshold level of 1.9 volts (when a 1500 uS pulse is passed through it) then planned to set that as VREF into an op amp comparator, but it obviously wouldn't maintain an active high signal for the entire period of the signal (unless the PWM signal was high for the whole .02 s. )
thought about adding an additional capacitor after the RC circuit.. but worried that will slow the response time down significantly..
also just ran into schmitt triggers today, though i was having trouble simulating them in pspice
any ideas?
thanks- brian
I designed a RC circuit with a cutoff frequency of 50 hz, and found a threshold level of 1.9 volts (when a 1500 uS pulse is passed through it) then planned to set that as VREF into an op amp comparator, but it obviously wouldn't maintain an active high signal for the entire period of the signal (unless the PWM signal was high for the whole .02 s. )
thought about adding an additional capacitor after the RC circuit.. but worried that will slow the response time down significantly..
also just ran into schmitt triggers today, though i was having trouble simulating them in pspice
any ideas?
thanks- brian