Schmitt trigger Switches between 2 output rails +/-M. Switch when inputs equal each other Use resistors to control this Inverting and non-inverting Schmitt triggers Inverting Schmitt Standard Schmitt
inverting schmitt with RC chargeup This is an astable multivibrator Negative feedback with RC causes switching f=1/(2RC ln(3)) Hambley p.809-812
555 timer Comparators give signal to flipflop Flipflop R high, Q low=reset Flipflop S high, Q high=set http://en.wikipedia.org/wiki/Flip-flop_%28electronics%29#RS_.28Reset-Set.29_flip-flop
555 monostable On-time to be announced by email. Hambley p.818-819
555 monostable Trigger is high, S is low, RS reset state, Q is low BJT is on as Q- is high, threshold shunted to ground When trigger goes low <Vcc/3, RS set Q is high Q- is low now, BJT off, C charges up thru RA When threshold reaches 2Vcc/3, RS is reset by top comparator Everything returns to start state
555 Astable circuit Prelab exercise 10kHz and 75% duty cycle Hambley p.820-821 Why are trigger and threshold tied together?
555 astable operation Start with vc=0, so trigger low, RS is set BJT cutoff, so C chargeup through RA+RB When threshold reaches 2Vcc/3, RS is set through top comparator, RS is reset, BJT is on C Discharges thru RB to ground thru BJT When trigger goes low <Vcc/3, RS sets, cycle repeats