lab

Help yourself. GCSE and A level electronics explained

Scmitt capacitor< xml="true" ns="urn:schemas-microsoft-com:office:office" prefix="o" namespace="">

Vout = -Vcc

Cap charges negatively, Vref is –ve

V- becomes –ve

When V- < V+, Vref is +ve

Cap charges +vely

V- increases

When V- > V+

Vout = -Vcc

Until Vcc = 0

One shot oscillator

Cap charged

Threshold > 2/3 Vcc

Bistable Q bar = 1 (resets it)

Cap discharges, output voltage falls

When Vin is NGT and voltage < 1/3 Vcc

Q bar = 0 (or Q = 1) so Cap charges

Square wave oscillator

Trigger = low

Threshold goes up

Bistable Q bar = 1 and T1 is ON

So Cap discharges

When V trigger falls below 1/3 Vcc

Bistable Q = 1

T1 OFF

Cap charges