LM555 output frequency drops when supply voltage from the regulator
Hi,
I'm using a LM555 timer to produce a frequency of 240KHZ & 50% duty cycle.
The circuit i'm using is Astable.
RA is 82ohm
RB is 200ohm
C is 0.01uF
RLs nothing
I built up this circuit and got nearly 240K frequency and 44% duty cycle
But when use a normal LM340T5 to produce a 5V to the LM555 timer...
The frequency immediately drop to 190KHZ
This cause my 3rd IC almost burn T^T
anyone can guide me to the solution?
Thanks
Best Regards
Wan Xi
The LM555 Circuit which provide 240KHZ & 50% Duty Cycle:
![[IMG]](proxy.php?image=http%3A%2F%2Fimg238.imageshack.us%2Fimg238%2F885%2Fastablefc1.png&hash=3959d1e40d75b3288e2717758510283d)
The regulator Circuit:
I'm using a LM555 timer to produce a frequency of 240KHZ & 50% duty cycle.
The circuit i'm using is Astable.
RA is 82ohm
RB is 200ohm
C is 0.01uF
RLs nothing
I built up this circuit and got nearly 240K frequency and 44% duty cycle
But when use a normal LM340T5 to produce a 5V to the LM555 timer...
The frequency immediately drop to 190KHZ
This cause my 3rd IC almost burn T^T
anyone can guide me to the solution?
Thanks
Best Regards
Wan Xi
The LM555 Circuit which provide 240KHZ & 50% Duty Cycle:
![[IMG]](proxy.php?image=http%3A%2F%2Fimg238.imageshack.us%2Fimg238%2F885%2Fastablefc1.png&hash=3959d1e40d75b3288e2717758510283d)
The regulator Circuit:
![[IMG]](proxy.php?image=http%3A%2F%2Fimg406.imageshack.us%2Fimg406%2F2186%2Fregulatorau9.png&hash=0feb612a932ed7d9192ae85f6e4de461)
Replies
-
sauravgoswamihey check your capacitor value,secondly somewere loading is goin on...
-
ahmed_hassan133first,be sure that your de voltage is 5v purly after loading,and also check this link for mor information
www.national.com/ds/LM/LM555.pdf
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