PWM generator

Papabravo

Joined Feb 24, 2006
14,655
Originally posted by charcle@Mar 14 2006, 11:46 AM
yup..i could understand that..but how could i change the duty cycle??
[post=14971]Quoted post[/post]​
In an analog PWM you change the value of some component. A manual method is to use a potentiometer to change a resistence. This resistance determines the rate of charging or discharging of a capacitor. Adjusting this charge/discharge rate is what changes the pulse width.

In a digital PWM you change the value of a register and that changes the value of the pulse width.
 

hgmjr

Joined Jan 28, 2005
9,029
Another approach is to use a triangle waveform that has a fixed frequency which is fed to one input of a voltage comparator and then vary the dc signal fed to the other input of the comparator.

hgmjr
 

hgmjr

Joined Jan 28, 2005
9,029
Originally posted by charcle@Mar 15 2006, 01:58 AM
still dont get the output.(simulation). After varied the potentiometer to half it still 12V.How to get ather voltages??
[post=15009]Quoted post[/post]​
Hi charcle,

Maybe you can sketch your schematic and post it so that our members can see how you have hooked up your circuit.

hgmjr
 
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