The published formula for frequency 1.44/((R2 + 2R1).C2) does not give the correct answer as given in published circuits or on-line calculators!
Example: R1=1K, R2=5k, C2=3.3uF by the formula = 62.3 KHz BUT [https://ohmslawcalculator.com/555-astable-calculator] gives 39.75 KHz in agreement with Gadgetronicx published circuit!
Please can someone sort this out for me? I need a 35 - 40 KHz generator..
September 01, 2023
All has come clear.. solved. It was all down to multiple errors in the circuit I got from GADGETRONICX..! They switched R1 with R2 so the wrong values went into the formula and then C2 was given as 3.3nF and it should have been 3.3pF. When corrected all became clear. Thanks for the forum.
September 02, 2023
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