Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: imarcianoloco on October 25, 2010, 10:14:49 PM
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well, here is a different form I discovered to run the 555 IC in astable multivibrator with only 1 resistor. I don't know if this circuit has already been invented before (probably has :P) but I've never seen it before in any diagram so hmmm... maybe it is new!! The duty cycle of the output is a constant 50% no matter what the frequency, so it won't work for PWM or anything that needs the duty cycle to be variable, but for a simple clock circuit it works great!
http://imarcianoloco.blogspot.com/2010/10/555-single-resistor-astable.html (http://imarcianoloco.blogspot.com/2010/10/555-single-resistor-astable.html)
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Hi,
I don't know if this circuit has already been invented before (probably has :P) but I've never seen it before in any diagram so hmmm... maybe it is new!!
Quite old hat. You'll find it in the CMOS-555 datasheet (and in numerous schematics on the net).
The duty cycle of the output is a constant 50% no matter what the frequency, [...]
If you use a CMOS version of the 555 (7555, 555C etc), you'll get quite close to 50% duty cycle, but with a plain old 555 you won't, as the output is far from rail-rail (and the duty cycle will most likely differ from one chip to another).