[TI-H] Re: [A83] Re: OT: Clock with resistor and capacitor


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[TI-H] Re: [A83] Re: OT: Clock with resistor and capacitor




One last reply,
	You are looking for a relaxation oscillator.  There is a time
constant for all resistor-capacitor circuits defined as RC or R*C.  This
is used to determine the charge/discharge time for a given capacitor.
It is logarithmic in nature and I cannot remember the equation off the
top of my head.

http://www.rwc.uc.edu/koehler/biophys/4g.html

that should help you!!!

Here is the schematic for the relaxation oscillator...

http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/relaxo.html#c2

and yes one transistor is needed.  If you intend to square off your wave
form try running it through an inverter or two!!!  If you cannot use
CMOS chips then an inverter can be easily made using one n-type and one
p-type transistor between Vcc and ground.
     
	      Vcc
	     ________
		 _|
	     ||
	|---o|| p-type
	|    ||_
	|	  |
 in --|	  |_______ output
	|      _|
	|    ||
	|----|| n-type
 	     ||_
		__|__
		 ___  gnd
		  _


lemme know if you need anything else





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