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Possible Options for the first Resistor/Capacitor Circuit - RC1

copyright cutcher 2001

 
 

turn on timed off - Set of timing units for RC 1  R2 C1 Time  20 M ohms 10 uF 120 seconds  10 M ohms 10 uF 60 seconds  4.7 M ohms 10 uF 30 seconds  20 M ohms 1 uF 12 seconds  10 M ohms 1 uF 6 seconds  4.7 M ohms 1 uF 3 seconds Remember that this is only a rough guide.  It is not a precise timer.	the schematic shows the related variations
manually speed up the timed off Use pin heads as a touch switch or Use a Push Button N.O. to instantly drain C1
Alarm stays active until you turn it off.   A hidden touch point of two pinheads is all that you need.  Use a small capacitor at C1 (.1 uF) and it will appear to turn off instantly (about a half second). Or use a Puch Button N.O. to instantly drain C1.
Time on Delay This circuit can be used to delay the activation of the circuit.  It can be used to give you time to set the circuit in a car alarm, for example, and have time to close the exit.   The value of the Extra R must be at least a fifth the value of R2 to work because the Extra R and R2 become a voltage divider - the voltage must rise clearly above the half voltage mark.  To give more time, use a larger capacitor.
No RC 1.   When the Inputs are Lo at pins 12 & 13, the circuit is active.  The circuit immediately turns off when the inputs go Hi.
turn off, timed on  This is really a modification at the output.  This was part of the exercise sheet in Exercise 2-2-5 Test Point 4. The RC timing table above is unchanged.  The output is reversed.