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23rd June 2019, 16:01 #1
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23rd June 2019, 16:27 #2
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Re: NE555 astable frquency
For a rough estimation, assume RV1 in center position, ignore diode voltage drop, use formula for astable operation in data sheet (R1=1k, R2=5k).

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23rd June 2019, 16:48 #3
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23rd June 2019, 16:50 #4
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Re: NE555 astable frquency
RV1 center position, 10k/2 is effective R2 value (ignoring the diode voltage drop).

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23rd June 2019, 16:56 #5
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23rd June 2019, 17:04 #6
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23rd June 2019, 17:07 #7
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23rd June 2019, 17:40 #8
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23rd June 2019, 21:27 #9
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Re: NE555 astable frquency
Since the frequency of the 555 doesn't vary much with the setting of the dutycycle pot, the value you get using 1/2 the pot resistance should be good enough for a reasonable estimate of the frequency.
Zapper
Curmudgeon Elektroniker

23rd June 2019, 21:47 #10
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Re: NE555 astable frquency
@Blue10
where did you find that circuit?

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23rd June 2019, 22:20 #11
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Re: NE555 astable frquency
That circuit is all over the internet.
Hey Google: 555 oscillator circuit with dutycycle adjustment
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